Like any fad, I think people are going to really want to play these games again in the future. Shame the DLC is disappearing - and I'm loath to buy any because I don't trust at all that it'll be accessible in the future, so having it tied to a console makes me scared any failure will me permanent loss.
Still, I'm tempted to check out the DJ Hero tracks anyway. That game was pretty cool, and the soundtrack was really well done in my opinion.