Yeah. But I think that GT5 is the game that will have long legs. (rest of PS3 life cycle)

Oh, yeah. This might be relevant.

For the time GT3 sold most of its sales, Ps2 had these userbases in the different areas.

Others: 3.1M  to 16.7M

Americas: 3.4M to 21.5M

Japan: 5.6M to 13.4M

GT3 sold this in that period:

Others: ~ 5M

Americas: ~ 6.5M

Japan: ~ 1.9M

So, with this, I would say this.

GT5:

Others: 5-7M

Americas: 4-6M

Japan: ~ 1M

So I see it as a definate 10M seller.

You're correct, but don't fail to remember that it is Halo, and Halo is colossal. Halo 3's prequel succeeded in selling approximately 2.4 million copies in North America in no more than 24 hours - did Gran Turismo 5's prequel do something similar?

I agree with this, GT 3 stayed in many top 20 bestseller lists for 3-4 or even 5 years in some places and is the very definition of legs in my book. I don't know why people suddenly expect this series to have half or one third of the sales from previous installments, makes little sense despite the relatively low (current) install base.

It will have massive sales and it will be praise by the critics.

It will sell 6.8 million max...

I will say 9-12 Million....

Ok let's use logic here...

GT4 did 10 millions on a userbase of 125 millions PS2. Why a GT5 on a 20-30 millions userbase would do better?

GT3 did about 14 millions on a smaller userbase right but also on the most popular console of its time. So the userbase increased very quickly as GT3 sales.

Now PS3 is a far different story. It's the less popular console of its time. Plus GT5 have solid competition this gen in the name of Motorstorm. Also no game on PS3 is close to 10 millions even GTAIV which is considered by many as 'the game of the gen'.

conclusion : GT5 will do around 4 millions LTD Worldwide.

GT will have a 200% attach rate due to people who don't even own PS3's buying the game.

life time sales of 22 Million.

Won't be as well as people think, the small userbase will hamper sales.

It will still be a million + first week.