I think with the User Base Japan will have when GT5 is released, Japan will probably have 2.1m sales within the first months. Europe should have sales of 5m Within the first months and US should be around 4mil.
I think GT5 will have little trouble passing 10m units sold.
I am a Gamer... I play games and not consoles. I have a PC and Console on which I game... I like games. End of Story!