Another factor in this debate which I'm not sure has been mentioned very much - 64 pages so far after all, is that we've been clamoring for GT5 for five years. Tourist Trophy has been nice, Prologue has been fantastic for many of us, GT PSP has been entertaining for some. But we wanted was GT5. Some of us began to make threats over it, so it's pretty clear we as a whole were getting rather desperate.
It seems to me that not only SONY wanted GT5 out for America's Black Friday sales superday yesterday, clearly, but that Kaz knew that to make the GT5 he wanted would take another three or four more years, at least. So he had GT5 built for expansion and patching, and I don't mean generically like a PC shooter which could have new maps and weapons added on, but evidently the game itself altered. It seems that Prologue was the first experiment in that regard, as it's the only racing game I'm aware of which had the physics engine itself patched.