Sonos does not share its plans, so nothing is certain. I’d agree with your first idea, but your second idea would be very difficult in Sonos’ current way of working. Not only would a multi-“room” (not “group”) Sub be able to connect to different speakers, but the speakers would also be able to function with or without the Sub, and be able to adjust their set up and know when they are being used with or without the Sub. They would need to remember and adjust different Trueplay setting for both situations too. The Sub would have to be able to adjust to different ways of being commanded - on a 5Ghz dedicated set up from a soundbar or Amp and on 2,4Ghz with other speakers.
And Sonos would have to design al this with the result probably being they sell less Subs, because at least some of the people wanting to use Subs in different “rooms” will eventually buy an extra Sub. Which they won’t do if your idea gets to be real.
