It's not rambling; we are quite clearly on the verge of a new console transition over the next year or two. As such, it makes absolutely no sense at this stage for Polyphony to be working full speed on GT6 for PS3.
While this may be true, the architecture Sony will go with happens to be the easiest, the most common and with dev tools that are very mature. We only have to follow the example of Vita to understand that developing for PS4 will be a lot easier than that of PS3, meaning GT6 will be up and running a lot quicker. PS4 will also be a better thought out piece of hardware, meaning that the graphical issues that have plagued GT5 will be eradicated.
That is also another reason of why GT on PS3 makes no sense, as the PS3 simply cannot handle what Polyphony are trying to do.
Or Sony and PD can release GT6

rologue close to PS4 launch, with a full GT6 12-18 months later, like what happened with GT3. That then leaves them plenty of time to comfortably develop GT7 for PS4, with no impending distractions of new hardware and a new generation, like is happening now.
I agree with everyone that we don't necessarily need new hardware to develop a great GT game, however, at this stage, it makes very little sense to have Polyphony diverting all their resources and making a full PS3 game.