The only three "big things" that I see that can really change the game for PS3 are a PS3slim+price cut, GT5 and The Agent, and the last only if it is marketed good enough.
Actually, I don't know the effect that Final Fantasy XIII and Versus can have on the PS3, I mean, yes, XIII isn't exclusive anymore, but it will sell a lot more PS3 units than 360 units (according to nielsen's survey of most-wanted games in america, which placed PS3's FFXIII above 360's, the one with ODST at the top, GOW3 second etc, can't find the link), not to mention the game's effect on the Japanese market, and maybe even in Europe.
Bet with Dr.A.Peter.Nintendo that Super Mario Galaxy 2 won't sell 15 million copies up to six months after it's release, the winner will get Avatar control for a week and signature control for a month.
