I think we'll see more battles in the coming years between Apple and Spotify over exclusive rights for the music of artists that aren't on either service.

Sidenote: I'm curious how iTunes Radio has done since they released it. I haven't heard from anyone who prefers that over Pandora or Spotify's offering. It'd be a large acquisition by their (or anyone's) standards, and I know I'm not saying anything revolutionary here, but there have to be discussions that have happened/will continue to happen about Apple buying Spotify.