I don’t have any inside info (like you, I’m just an end-user), but my take is that the Sonos gear will continue to work, per Sonos, for the ‘foreseeable’ future. And as @Rugby mentioned above, Roon => Sonos functionality should continue to work as well. Who knows, the Roon => Sonos connection may even offer the older Sonos gear a longer useful life than directly from Sonos! Of course, this is anyone’s guess – no guarantees.
In my case, I’ve already transitioned three of my six Sonos zones to Roon, with a Roon Nucleus now directly driving my old-but-still-fine Peachtree Audio (24/192 USB input) DAC, with two other Sonos Connect boxes now replaced by a pair of Sonore microRendu units, streamed-to via Ethernet from the Nucleus, and driving their respective DACs and systems (which were already in place, but previously had been driven via S/PDIF (coax) from the Sonos pieces, but now using USB inputs on those same DACs).
I’m not too concerned about the Sonos legacy gear’s lifespan at this point, especially as a Roon user, but thought I’d post the info received from Sonos earlier today, in case of others trying to make informed purchasing decisions about new equipment.