Alexa+

Sonos doesn’t integrate Alexa into their speakers as a system, what they provide is a method by which your commands are sent to an Alexa server, which then interprets your commands, and sends back to your speakers certain commands.

Which means it is up to Amazon as to whether they send your Sonos voice commands to an Alexa + enabled server, not a choice by Sonos. 

When Sonos Voice Control came out, I made the choice to no longer attempt to integrate Sonos and Alexa (and eventually Alexa+).  Echo devices are pretty cheap, and Amazon was always going to come out with new features that Sonos was going to lag behind in implementing with questionable profit motive.  The early examples was the ability to make voice calls through the device.  I get that people don’t want to have 2 ‘speaker systems’ in their home for aesthetic reasons, but I find that I place my Sonos speakers where speakers should go, and echos closer to where I want a mic to be, so it isn’t that much of an issue.

I say this because if you are considering purchasing echo devices, I would suggest you still keep your Sonos speakers and see if a more dual setup makes sense for you.

Also, I don’t know that Alexa+ is that much of an improvement over Alexa.  Not all of my devices are Alexa+ eligible, apparently, and I have not used any features of Alexa+ that aren’t available on Alexa, although that could be that I just haven’t explored enough.  The only thing I’ve noticed is that Alexa+ tries harder to sell me Amazon.com stuff.

I don't want a dual setup. 
 

I would say it is strategically important for Sonos to already support Alexa+.  
 

The Sonos CEO should be in key meetings to make it happens. 
 

Sonos’s software strategy and innovation is critical.   And the lack of communications on this topic is concerning.