From a business standpoint I think they would be smart to follow Netflix's lead. I don't know how accurate it is but people say Netflix uses all their analytics to drive their content production. I can easily see Spotify using all the data on which songs people listen to all the way through and which they turn off half way through to try to make some computer written hit songs.

Of course Theodor Adorno would turn over in his grave when that happens (as if it basically wasn't already happening).