You bring up a good point, and it's one I've been wondering about a bit lately. That is, why hasn't Microsoft shelled out for exclusivity rights for GTA? Probably because Sony is paying them big bucks, but still... plans for an Xbox version were scrapped (sadly - I would love to see Liberty City rendered on the Xbox) so it's all PS2 & PC now. Another big one would be Tony Hawk, because it's retardedly popular.
All in all, it doesn't matter much to me which consoles survive. There's room for two of them and possibly three, but if not, we'll end up with a cheap console and cheap games for it. Can't say that I'll complain too much about that.
--dave, lover of cheap games.