I get what you’re saying, but Sonos works differently than a normal speaker. It is playing the music, not your other device. The app is a control. So if you turn on music and leave with your phone, the music keeps going. When other people connect, they see your music and services, not theirs. It’s its own thing - not just a speaker.

That said, your point about, “will it continue to work if sonos, the company, is shut down?” Is a valid one.