I'm just surprised Spotify hasn't done more to let artists create brands. I'm imagining something like Facebook pages, and you have a custom newsfeed on your home page that artists could post to including stuff like "new t-shirts are available" and advertising concert tours. It could be based on who you listen to the most/recently instead of explicitly following people.

Apple's Ping tried to do that stuff, but it was a massive failure due to other reasons (everyone hates the iTunes app).