The one thing they gotta announce when they announce the game, is that all the downloadable content can work with the second one, otherwise no one will buy it. No one wants to fork out all this money for a game if it's only got like a one year lifespan before the new version comes out. If harmonix want to have a huge DLC library, they can't make it incompatible. They need to do more what singstar has done, and just release new discs (volumes) rather than releasing a new game IMO.