That was the original stance, it's unclear to me if it still is. The post they made seems to be intentionally vague...
“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...