I think GT5 sales wont be as spectacular because GT3 really was the 1st photorealistic (or near photorealistic) racer. That was the reason I wanted a PS2. Now basically all racers are photorealistic and we have had so many this generation already. Unless you want a racing sim and you either dont have a 360 or have a PS3 you have had plenty of choices for photorealistic racers. If you have a 360 and want a photorealistic sim you have had two already with Forza 2 and Forza 3. So overall I believe the demand will be down.
Nevertheless hardware boost by GT5 will also be negated by GT5P release and the fact that when GT5 releases well over 30 million people will already have a PS3 and like 5 million of them will have GT5P.
Its libraries that sell systems not a single game.
