I liken Gran Turismo 5 to the concept they had in 1984 that "War is Peace," or that the only way to keep a stable civilization was to be in a constant state of war, and to always want but never have peace. The only way to keep the racing game genre alive and well is to have development and innovation on other games, while people still remember, even falsely, the wonders of the previous GT games.
You must never have GT5, Dave. It is all the keeps civilization from crumbling beneath us. But you must continue to want it.