if they did do GT for PC, ohh man. You could have no limits to graphics capabilities and physics simulation. It would, however, require a pretty good controller to play it well, though. But you could have backround and scenery graphics like crazy! Although this would only be on a high-end computer. We're talking SLi, athalon64, 2+ gigs of ram. And at least what, 15 gigs of HD space?
One definate plus to a PC GT is that you could easily race online, not to mention download new cars every month or so. The car list would never have to be outdated again! Because, let's face it, by the time they finish a GT, its already almost a year behind the current models.