Sonos recently announced that they will stop supporting several older products. All of these products date back to 2015 and older, so chances are good that you'll be unaffected if you've purchased Sonos products more recently than that. Still, this is quite the blow, considering how many of these older devices are currently installed and still being used.
Sonos mentions two important details in their letter to customers. First, the older devices won't simply stop working on the day of reckoning (sometime after May 2020).
We don’t expect any immediate impact from ending software updates.
Those devices will simply stop receiving software updates necessary to maintain existing features or add new ones. How long those devices continue to function is unknown. It could be days or weeks, or even years. It may depend on the specific service being used. Perhaps Pandora works fine for a year, but Spotify which is known to pull some really annoying moves all on its' own, stops working after a month. We'll have to wait and see.
As changes are made to technology in the future, particularly by music service and voice partners, access to certain services or features may be disrupted. An example would be a music service partner issuing a new update that isn’t backwards compatible with legacy software.
The second detail is that Sonos is offering a 30% trade-in discount toward new equipment purchases. They stipulate that customers must tell them the serial numbers of the existing equipment, which implies that they will most likely make the trade-in units non-functional. Still, it's a good way to ease the pain of having to purchase new devices, which could get pricey.
So, do I Upgrade Now?
Unless your installation is 'mission-critical' (perhaps you're a bar or restaurant where an outage could be very inconvenient), it might be best to wait until you're affected by the changes. It's possible that the lack of software updates will simply mean you don't get a new feature that you never had before, and won't miss anyway. It's also possibly however, that you'll lose access to your favorite streaming service.