sonos app as “standalone” streamer

How would this differ from using, say, Amazon Music on a mobile device, playing via Bluetooth or an aux cable to Sonos portable speakers? Are you suggesting using the mobile wifi as the connection from app/device to Sonos portable speakers? 

The Sonos app is a controller, and doesn’t stream any audio at all right now.  It also doesn’t store many of your system credentials, like logins to different streaming services.  Adding this feature would be a pretty big technical change.

I also don’t think many streaming services would allow Sonos to stream their service on a mobile app.  They want as much of the experience, audiio, features, etc, under their control as possible.  Sonos is a exception since there is no real way for streaming services to get that sort of control over the Sonos devices without going through the Sonos APIs and the Sonos app.

It should also be noted that Sonos would not likely be able to charge for this feature, and it’s not likely to bring in more product sales indirectly.  They also would not be able control whether the audio is played through non-Sonos speakers/headphones or the mobile device itself, since the OS is responsible for that.  

I get why a music streaming aggregator app, whether made by Sonos or otherwise, would be great for consumers, but it’s seems highly unlikely to happen anytime soon.