Quite frankly, I'm hoping for something a bit more akin to Spotify. The ability to add any songs to any playlist, and then listen to them for free on shuffle. I don't purchase many tracks individually, but I find myself purchasing a lot more now than I used to because of Spotify. I'll add a song, and listen to it for a few days on shuffle, and find myself wanting the ability to listen to it whenever I please. So I'll head over to itunes, and buy it.
Were Apple to make their radio something along those lines, it'd be a much more seamless experience for me.