Since the Sonos app is effectively a remote control for the software on running on the speaker, I wouldn’t see there being any advantage to having the controller run on cellular data. The speaker itself would need to be on a network, something that doesn’t exist away from a router or even a hotspot device. 

Thanks Bruce

The advantage would be to get to the Sonos play lists, music and Sonos radio rather than having to load another music app and duplicate those play lists.

If the ambition is to develop the remote listing experience through portable speakers, headphones and earbuds then surely the ambition should be to get the app portable as well.

The app on your phone doesn’t ‘play’ anything, the device that ‘plays’ is the speaker. The app on the phone is just the interface, telling the speaker what source to reach out on the network to ‘get’. 

I get where you want to go, it would require a complete rewrite of the underlying software that Sonos uses to operate the Sonos ecosystem. It’s not impossible, but I wouldn’t hold my breath, either.