^^
Yes, most probably in the next 3-4 years PS3 won't reach the same user base PS2 reached in the same time span. In favour of GT5 there are huge sales of a simple demo, long waiting and current PS3 sales performance, very good, as it stayed high even during dead weeks and competitors' big launches weeks. We'll have to wait and see, as there are too many factors in favourr of one or the other to really be sure.