I think it was FishyJoe's or Mrstickball that said Forza 2 sold around 2 million before bundling. There are quite a lot more X360's now than in 2007 and there isn't much competition: on the 360, the only sim-like racer besides Forza is Race Pro. So I'm going to say Forza Motorsport 3 will do at least 2,5 million on its own.
About GT5? Well, it'll be massive. It's Playstation's Halo, for fucks sake. 25% attach rate at the bare minimum - with the current ps3 sell-through, that's 5 million units. Besides, GT fans are thirsty - check this:
GT4 release: december, 2004
Forza 1 release: may, 2005
Forza 2 release: may, 2007
Forza 3 release: sometime in 2009
GT5 release: TBA
GT5 will be huge - not LBP huge, I mean reeeeaaaalllyyyyy huge. The glorified demo they released in december 2007 sold almost 3 million units. GT5 will do that first week.
Current-gen game collection uploaded on the profile, full of win and good games; also most of my PC games. Lucasfilm Games/LucasArts 1982-2008 (Requiescat In Pace).
