Indie bands finally get their music to more people and see profits rise for them.
Mainstream bands want to get in the game, but aren't fluent with the concept so they pay Joe Schmoes who are capable of using the service to bring the music to us. More people get paid.
Artists and record companies soon realize the old way of selling music is dead. Jimmy Page falls to the floor weeping, "You win Rock Band... You win..."
Rock Band soon becomes the only place musicians come for video games, Activision crumbles from it's own greed and self-destructive ways. (Well, this may be a bit bad...)
We finally get some Queen, there is peace in the middle east.