I imagine they could make GT6 easily in 3 years. Therefore, I'm banking on about 8 million sales.

 And technically i could fly if i jumped of my balcony but i can promise you that sure as hell is not gonna happen.  Just look at time between GT3 GT4 GT5 release dates.

yes GT5 can do it. As for prologue it will reach 3mil before GT5 comes. I highly recommend prologue to anyone that is thinking about it, i havent played a better racing game. Online is great even though i dont like it when i get disconnect, 2-3 times in 10 races, in the middle of the race. I guess this occurs when the host leaves the race.

To conclude, if prologue is just a taste of the real thing, then when GT5 comes people will go mental. It can define racing games once more, so it can reach 10mil in its lifetime. Most of the people dont know about games and buy a console only to play 5-10 games in a generation. These games include GT.

 It has, our numbers are not up to date, according to Sony, it has sold 9.92m

Anyway, this game will come out spring next year, so I would expect the user-base to be over 25m, so 8 or 9 is certainly possible, and it will get more people to get PS3s, so it could make 10m

due to the popularity of the game, gt5p is going to do very well, for a budget title thats super,

 but it wont match the full gt5 out next year, i belive by june 2009 the ps3 install base will be very big, im actually betting on a bigger base than the 360 by that time.

10million is a huge number but its possible, id say more realistily 7-8million

That was when the install base of users able to buy the games was larger than that of what the N64 or GC had. The case isnt what it is now. While the game will actually have great legs and exploive first week sales, it won't be one to reach the 10million mark. The story would be different if the game were sold under a 30 or even 20million userbase (PS3 owners) but this isn't case.