Gran Turismo has been in living rooms since as far back as I can remember. But due to limited hardware, and hardware so unique it was hard to develop. This has caused infinite delays. And ties Polyphony's hands, due to the sacrifices, and compromises it has to make in order for the game to run on the limited hardware.
Well with Sony releasing the PlayStation 4 using X86, Sony has made it easier to design games. But the problem still remains. The hardware is cheap, limited and in the Pc x86 world the CPU/GPU is considered to be quite slow and limited.
For perspective and  Keeping to the providers of the Hardware to the PS4 AMD. the current chip inside the PS4 is at a performance level/Delta of 100%
AMD has high end Discreet GPU's that are almost 200% faster at double the resolution of 1440P or even 4K! So at the same resolution its almost 400% (900p, 1080P)
if we include Nvidia here that number goes up to 300-600% quantifiable performance

With GT 7 pretty much nearing completion. Being created on the X86 low level API platform. And Direct X 12 incoming for Windows 10.
There is no reason to overlook the PC for this monumental game. That deserves to be honoured with the ability to be played on the PC in all its amazing glory.
Also being already designed on the same platform, makes this an easy decision. So lets make it a no brainer! 

Kaz_Yamauchi must design Gran Turismo's next version for the PC. to realize its full glory. 4K high quality, and amazing frame rates. Help me get The relevant parties attention