Very true. So unless these exclusive deals are already made I cannot see where the system sellers are going to come from. Even Epic games are moving toward multiformat games.
I don't doubt that MS have their first and second party developers busy on launch titles (no doubt built in Kinect features are mandatory). 343 and Turn 10 studios are both capable developers. But they are going to have to rely heavily on Rare and Lionhead studios, both have lost all (most) of their talent this gen.
I guess its far to early to tell, but based on the last year's of this generation Sony definitely look like they are in a better position. Despite the PS4 being a "all or nothing" console this time around.