Guitar Hero: Bananarama?

No, this game doesn't exist. But it does pose the question,...where does it stop? It seems like the Guitar Hero is just as successful now as ever. With band centric titles like GH: Aerosmith and GH: Metallica, a formula has been created that seems to work.

Rumor has it that a Van Halen edition could debut before the end of the year. So with that being said, where does it end? And do you prefer purchasing a band centric game, or would you rather have them release as DLC?