I’ve had both systems, and still have 2 PS3’s and an Xbox360. I rarely game no the PS3’s anymore, mainly just use them as my bluray player.
Sony has always botched old games with their systems. When I got the PS3, I was hoping to still be able to play some of my old PS2 games I had laying around, but I couldn’t.
I think Microsoft would be really stupid if they don’t allow for used games on the new Xbox. That would hurt their sales in my opinion. That would probably rule out even renting a game from Blockbuster or GameFly. You couldn’t borrow your buddy’s game and you couldn’t go to GameStop to trade in or buy used games anymore. That could be a huge blow!