I would think Gran Turismo 5, that game is THE racing car game of all games. The only problem is being exclusive to PS3 while GTA 4 is on two consoles, but still I think that has the best chance.
For some reason I think Final Fantasy sells are going to be lowered because of the two games (normal and versus) in that some people may buy one first and may not buy the other at a later time, also PS3 isn't so huge in Japan to warrant millions of sells in that region.