What happens to Play 3 speakers if Sonos goes out of business and/or no longer supports the Sonos app?

Nothing? You've already downloaded the app, so the only thing that could potentially happen is that we get no new features.

It's possible that over time, companies that have streams might change the location of the stream, if they release a new kind of software, for instance, and then you'd lose access to that stream. But that's pretty unlikely these days.

And you'd still be able to play local music just fine. And, if they were going to go out of business, which seems most unlikely to me, I'd be willing to bet that someone would purchase the assets of the company and continue in some format the business.

But honestly, if they were to burn down today (which is unfortunately likely in a physical sense, with the fires in California), you'd see absolutely no change in your speaker experience. Since none of the streaming of music goes through any servers at Sonos, but come directly from the service providers like Apple, Amazon, Google, Pandora, Spotify etc, there'd be no change whatsoever.

Sorry I guess I didn't clarify my real point in asking that question, so that we don't have to speculate what is possible or what may happen in the unlikely event of Sonos going out of business. The real issue is that a $300 speaker, or pair of them at $600, does not come with rear input jacks for a hard wiring option. Worst case, if Sonos did go under (for whatever reason), and support for their app ended, you could end up with an expensive pair of door stops. Speakers in this price range should have such a simple feature/option for wiring to an existing system, which would also dramatically expand the potential use of such an investment, rather than limit its use.

So, in that case, the currently existing PLAY:5s and CONNECT and CONNECT: AMPS would all spontaneously combust, and not be available for sale on eBay and other resell locations?

I'm not sure I understand where you're going with this, unless it's a simple complaint that you want a line-in available on all speakers.

Do you work for Sonos, or what?

It's not a complaint. It's a lack of a key feature that should be there...and it would be a really nice option that would definitely favor the purchase decision I'm considering...

And the suggestion that I would have to make further Sonos system component purchases at multiple hundreds of $$$ to overcome this possibility is just plain ludicrous. You must be a Sonos employee in disguise on these blog posts. Thought this community was an open forum?

With more direct casting being pushed out probably less of an issue. But I imagine in the very unlikely case of it all going belly up - some enterprising people would come up with a solution allow speakers to continue to operate.

It's a lack of a key feature that should be there...and it would be a really nice option that would definitely favor the purchase decision I'm considering...

It would also be a potential pain in the rear for an already rather busy Sonos Support, as the amount of customer complaints concerning line-in audio delays et al would most probably go through the roof. Something you can see on this board quite frequently with Connect and Play:5 customers.
It's an understandable business decision to restrict these issues to those products with respectively small sales numbers.

What does stopping support for the app actually mean? Why should the system stop working over wireless any more than via line-in? Some people might see an end to updates as a positive feature.

Sonos representatives are clearly destinguised on the board.

The poster was clearly being light hearted and you seem way serious!

Even if you bought a line in equipped unit, it would need continuing support else it will slowly degrade. Sonos is now large enough for continued business existence even if ownership were to change.

No guarantees for that happening of course, as there are none for your lifespan. Or for anything else, except death and taxes.