@Mars and Darth.....MGS4 and FF13 combined will not manage the numbers of either SSB or Mario Kart, wheras GT5 does at least have a chance of selling similar numbers, though i expect it to only be about 2/3 of the top selling of the two. (about 7-8 million...though that will take a while seeing as PS3 will have a userbase of less than 15 million when it releases...assuming i am right with a summer 08 release)
GTA4 i am very unsure about due to the franchise never launching on an MS system at the same time before, and again due to the userbase issues....but i suspect it will sell a lot of copies on 360, but not really increase hardware much, whereas on PS3 it might not sell as many immediate copies, but will help hardware more and have better legs.
even so, i dont think the PS3 version alone of GTA4 will manage 8 million, something SSB and MarioKart have a really good chance at. (i would guess 10M+ for both)
