I just found this [0] in their forums from Sonos employee:

“In May, you’ll be able to decide if you want to keep your legacy devices operating with your modern devices, and you’ll be able to put them all into a non-updating legacy system”

So they are actually reversing course to a certain extent.

If there’s one thing Sonos has shown throughout this mess, it’s that they’re really quite poor at communicating things clearly.

[0] https://en.community.sonos.com/ask-a-question-228987/questio...