flagship on 05 October 2007
If you're looking for the total number of copies sold across all systems then most likely the game has yet to be announced.
I think Super Mario Galaxies is a good choice but the Wiis focus as a group oriented system will stunt sales. Mario 64 was such a behemoth because it WAS the reason to get an N64, I expect SMG to sell really well but 15 million + copies would be pushing it.
GTA4 won't be #1 simply because a bigger and better GTA will follow it in a couple of years. GTA3 was topped by Vice City sales which was topped by San Andreas.
I think this generation is going to be interesting because the top selling game may well be a multi-plat which sells heavily on both the 360 and PS3.
