Looks like Gran Turismo 7 is not that far away. According to Sony it will be series' first entry on the PlayStation 4. Speaking with Famitsu, Gran Turismo producer Kazunori Yamauchi commented on the PS4's memory, cpu capabilities and noted that GT7 will be done in a "a year or two."
The full quote:
“The PlayStation 4′s large memory size is a unique trait, but in terms of CPU performance, the PS3′s Cell chip, while difficult to handle, is really capable. They both have different advantages. Besides, I think the online community aspect, one of the most fun parts of GT, doesn’t have anything to do with the platform. The PlayStation 4 game which we’ll likely call GT7 will be done in about a year or two, I think, and I think the community aspect’s going to be vital there as well.”