>If you are a subscriber to Google Play Music, good news, you get a YouTube Music Premium membership as part of your subscription each month. Calling it now, within 5 years there are at least 5 different Google services for streaming music (up from 3 now, Play Music/Youtube/Youtube Music) at least 2 of which are also somehow messaging apps. It's even plausible, one for VR music videos, one for streaming in your self…
YouTube already includes comments and a chat on live streams, so close to a messaging app ;-) Seriously though, YouTube is not a music service, or at least it looks like they don't want it to be, since the interface isn't really great for that case. It also kills phone battery if you use it that way, so YouTube music is an experience upgrade.
I have to disagree there, it's become my new de-facto music service on my desktop/tablet, at least since I failed to properly move my iTunes database and lost/unorganized large parts of my music collection.
The autoplay and mix playlist features are great for discovering new artists, even tho the algorithm can get a bit repetitive and after a while starts populating many lists with the same songs, having the music videos to many songs is also a great added bonus.