"We are working on a way to split your system so that modern products work together and get the latest features, while legacy products work together and remain in their current state. We’re finalizing details on this plan and will share more in the coming weeks."
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.