While Guitar Hero is a licence to print money, DJ Hero is less of a sure bet. For all we know, it may stink up the joint! That's not bothering Activision, though, as they're already looking for more developers.
More developers, and more artists.
According to GI.biz, "at least one independent UK games developer" is chatting with FreeStyleGames about working on DJ Hero 2, and one of the famous DJs already being approached is Qbert.
Hope the game goes well, then! Activision recruiting talent for DJ Hero sequels [GI.biz]