I own over 20 devices currently, and have been part of the ecosystem since the first PLAY:5 was released, or there abouts. In all that time, more than ten years, one time has there been an issue with Sonos itself, something they resolved with a software update fairly quickly. Every other time I’ve had issues have been a result of problems in my own network. Sonos, being a network device, does rely on a clean network, and is slightly more sensitive to network issues than a standard PC, due to the way they work, constantly talking to each other, to the outside world, and to the controller device. But all of those issues I’m speaking of were in my network, and not in Sonos software. Following good network practices will keep any issues at bay. 

Sonos doesn’t do everything I want it to, but it does do everything it is designed to, and quite well. I do indeed recommend it, and in fact have gifted new devices to friends, as well as given my old devices to other family members as ‘first’ devices. 

I started investing in Sonos in 2011, moving away from wired audiophile systems when they started getting ahead of the music and I have no regrets even though I have chosen to be left behind on the S1 app, because I see no sense in jettisoning half my 12 Sonos unit system to keep up with what is mostly fluff as far as listening to music in S2 is concerned.

We are now in 2021 and there now are viable, even cheaper, alternatives to Sonos that did not exist in 2011. So while I have no issues with my Sonos hardware that still performs flawlessly - the reason I refused to leave it behind in a move to S2 - I would not buy Sonos today for fear of the same thing happening in some years. But to your point, I don't see that happening as early as in 3 years. 

I have also concluded that it is better to have the smart bits in a cheap front end, wire connected to the sound producing kit. That way, replacing just the smart front end is financially doable, even every three years. For example a combination of an Echo Dot with a pair of good quality speakers will easily replicate sound quality obtained from Sonos, and the Dot can be changed as frequently as more featured ones arrive. In fact, budget permitting, one can get even better sound quality by investing more in the speaker side of things because obsolescence will not be a factor for that investment - some of my old kit working just fine in conjunction with Sonos is twenty years old. Availability of long term after sales service support becomes important though.

In your case, even if the Sonos Five is obsoleted by Sonos in the future, the fact that it has line in jacks will allow it to play with any smarter device that is released in the future, by Amazon and the like, as long as said smarter device has audio out jacks and as long as the Five hardware still works. The Ones, lacking such jacks, are not as future proof. Most of my zones are built around line in jack equipped Sonos units, and my interface to these is via Echo units hard wired to their line in jacks. I rarely use the Sonos controller app these days.

I am sure that others here will tell you not to worry and go ahead - which is a valid point of view, especially for people that want a all bundled together fit and forget solution. It just no longer makes sense to me.

More flavour in the linked thread started recently by a Sydneysider if you are interested enough to read:

https://en.community.sonos.com/ask-a-question-228987/wireless-speakers-as-an-alternative-to-sonos-6861517

It’s not remotely likely.  Sonos commitment on this is that they will continue to support with updates and new features that apply for 5 years after a product has been discontinued at a minimum.  The Five was released last year, and the Sonos One a year or two before that, and based on Sonos product history then tend to keep products on the market for a very long tine.

It’s important to be clear that Sonos did temporarily have a policy where customers had the option of getting a 30% discount on new products for voluntarily agreeing to recycle their old units.  After a few months, that policy changed where you no longer had to recycle your old units, you could continue to use them or sell them as you wish.  Like Kumar, some of chosen not to upgrade to an S2 system and continue to use there current speakers as is, while receiving periodic patches for security updates...no new features.

So really, speakers you buy today will likely be fully supported for 10 or so years, with minimal support after that point to continue to use the system as is.

History certainly suggests this; but one thing to think about is that future tech breakthroughs may happen at a faster pace than have happened in the last 10-15 years in the space of the larger universe of smart homes of which Sonos type solutions will be just one subset. Which is why the quote uses the word “likely” I guess, and I use the word “may” because one never knows when breakthrough innovation will happen and what form it will take, almost by definition. For instance, almost no one in 2015 saw the Echo coming - Sonos certainly did not and had to resort to layoffs and the like because of its success in just 12 months after it was launched in the market by Amazon.

Say you have an old Sonos device, pre-2011. It might have could have 32 mb of storage or less and 32 mb or Ram or less. For playing songs from your music library, which is what Sonos was first designed to do, that works. 
Today, we have to carry bigger files to more speakers at once. This includes Dolby 5.1, Atmos, Hi-Res Streaming audio services including Hi-Res Sonos Radio and Alexa/Google assistant. The speakers/amps with little processing power and small amounts of storage and Ram will have a hard time keeping up with True HD Atmos audio track steaming to a 5.2 setup (and that’s if you don’t decide to also group this with other speakers.) 

Long story short, audio files can only get so big. There would have to be significant features like Dolby 13.2 (which S2 can probably deal with) that would cause speakers which now have 1gb storage and Ram to struggle with. Video files are getting bigger every day for HD to 4K to 8K so if Sonos was a video streaming device, I’d be worried. I wouldn’t worry about audio streaming since it seems they out more than enough memory in the new speakers to last many many many years. 
Ive attached a chart to give you an idea. 64mb devices seem to be the cut off at the moment for  S2. We have a long way to go.

As houses get smarter, I’d expect present boundaries between various devices to get blurred. It is very hard to comment on adequacy of present hardware, five years out, with that happening, and extrapolation from history may breakdown.  

I would not be surprised if the soundbars became light hubs like a Hue sync for gradient light strips or something all those lines. I can’t disagree with that. 

It’s getting way off topic, but if you look at history of  AV, there always seems to be a push and pull between All-in-One devices and a component based system   The problem with all-in-one devices is they tend to be mediocre at everything they do, or they do one thing really well (the main selling point) and everything else mediocre.  As an example, a typical smart TV will also have embedded apps and their own speakers.  The video may be great, but the apps are mediocre and the speakers crappy.  To get the best experience, you’ll get an external streaming device and your own speakers.  With a component based setup, you buy a products that do one thing really good, and typically integrate well with your other things.  When an improvement happens in one particular area, you replace the component, not the whole system.

That’s not to say that all-in-one devices aren’t good.  They are usually more convenient and easier to use than a component setup, and sometimes mediocre is good enough.  This is especially true when a new tech or standard has matured, until the next improvement comes along

I’d agree that lines get blurred at times, but I wouldn’t say that everything converges towards all-in-one devices.  I like the idea of going with a component approach whenever it makes sense.  If your smart speakers are good for playing audio, then you won’t need to worry about replacing them with whatever new tech in other areas comes along in the next few years.

That is exactly why I have moved away from bundled Sonos solutions by resorting to Echo for the smart side of things. Fortunately in my case, both Connect and Connect Amp can serve just as well as HiFi components for all the non smart functionality they carry. The move was prompted by a combination of the S2 thing and the complete lack of interest shown by Sonos in Alexa integration for India, but now this looks to be more than a workaround - I prefer the Echo interfaces to music playing that I get this way from what the Sonos controller app provided me earlier. And no matter what rolls out in the future in home audio or smart homes, as long as the excellent Sonos S1 hardware works in dumb mode, I am not affected. I am pretty sure this will be the case even if - worst case - Sonos goes the squeezebox way sometime in the future and server support is pulled. Especially because my interest in enhancing the audio side of TV is limited to what I get today from a simple stereo speaker augmentation of the sound from flat TVs.

Correction! 

The squeezebox server based system is alive and well.  Logitech stopped device manufacture but the software is still actively supported and updated.  Just sayin'..... 

Lol. Noted. Who supports it - some company, formally, or is it an open source initiative? And does it retain all the functionality existing before the plug was pulled on it?

PS: and FYI, my Raspberry hosted My Media for Alexa that you helped me set up continues to work flawlessly, allowing me to play local files on Echo via voice command, with album art as well. The only miss there is that I can only play via voice command, unlike in the case of Spotify where I can also cast from the phone to Echo, silently.

The squeezebox Community have essentially inherited the media server software (as open source) - the support forum is still hosted by logitech.  The server software is massively improved compared to the earlier versions with many active Plugins.  

In my case, I limit most of my sonos use to Audible, and use squeezebox for everything else.  One brilliant feature if you use the free picoreplayer software on a raspberry is the dynamic connection for Bluetooth headphones/speakers. 

To get back to the original question from @Wobind I’d say “yes”  - it is good and it is worth buying into. Some users have experienced system issues and it seems the network demands for sync’d multiroom audio is greater than that for just a printer on a network. If you have problems (as I did, many years ago) there are folk on these forums that freely offer their time helping guide you through troubleshooting and resolving most issues. And as already said, Sonos have committed to support products for at least 5 years after they stop selling them. 

I reckon the OP has all he was looking for and more, so the rest of us may be pardoned for chewing the fat a little…

To the quoted, I have heard this said of Echo devices as well - that they demand less from the network than Sonos, even where multi room is not in use on the latter.

Here is what I don’t have a good handle on - do Echos working in grouped mode also have lower network demands than Sonos? All I know is that mine do groups just fine on WiFi - Echos do not have a Sonos net equivalent.

Note to the OP.  This thread seems to have been overtaken by two of the most vocal Sonos critics - One who is bitter over the S2 change and the lack of Alexa in India, and another who has a strange, but quaint fondness for a system Sonos put in the grave going on a decade ago.  Please don’t take these vocal, but anecdotal posters sway your analysis.  The vast majority of Sonos users are quite happy with their systems.  

Hi there - just wanted to say thank you to everyone who commented. I have just bought a turntable too so I am going to buy another five so I have a stereo pair, and that would put me in for 4 speakers in total and I’ll see how that all goes.

Wanted to express my gratitude for the comments and interest folk showed. One thing that does seem to be excellent about the whole ‘Sonos’ thing seems to be the community. Reading through these posts it is interesting to see the support and sharing.

Thanks again guys !!!

Heres a list of the devices currently active on the system you claim was buried a decade ago.   Notice the various headphones in use. 

Rumours of this system's demise have been greatly exaggerated.  Nevertheless I guess the OP will enjoy his choice. 

I’m sure there are people still driving AMC Gremlins out there too!