the game must be ready to be put on discs sometime in the begining of november, otherwise they cannot honor the pre-ordered copies.
Actually, everything about Gran Turismo seems to break the mold.
When a security hole reared its head in the fall of 2010 - speculation based on some scant remark by a SONY spokeshuman back then - GT5 was delayed all of three days while PD made a fix for it, and the existing discs were swapped out of loaded cases. Three days before release, mind you, and we got our copies in America. It seems that among all the developers out there, Polyphony Digital is one of those who really does work on their game till the last minute.
I suspect "last minute" this time to mean three weeks, maybe two, but still, that's not the usual margin. For most devs, it's 30 days or more when they call it quits and button everything down.
As for GT7, it cooouuuuuld be ready in two years, but I'd think this would cut into GT6 sales. However, this is a strange situation for Gran Turismo to be in. VERY late in the PS3 lifecycle, so late that GT7 is hanging in everyone's minds already like a growing cumulonimbus, and I have little doubt that both SONY and PD both would like to push a GT7 out the door just as soon as they can. Kaz is right that the PS3 is a powerful beast, but the quirky architecture and limited ram hamstring it. For instance, there's no Movie Maker because of the ram limitation. That's one big item that will be easy peasy on PS4, and then there's better weather, time of day on all tracks because of a seriously potent GPU and eight full CPU cores to drive it, more room for more involved A.I. code, better physics including a more living world with wind effects and independent objects like flags and trees, spectators etc, much better shadows because of copious ram to hold the maps, more powerful tool aps like Course Maker III and a serious Livery Editor, lots of room for lots of long detailed audio samples...
PS4 will make a lot of things possible that PS3 could only dream of, and I'm sure the team is chomping at the bit to get to that next gen architecture.