I think you just proved my point. There were no tech issues to solve because there was no copious alpha, no dynamic weather and no dynamic time, because they weren't doing them. PD had no problem in taking GT3 and just bolting on more cars, tracks and features, and I have never disagreed that a GT6 with more cars/ tracks, more pertinent features and more logical design could easily work on PS3. That game should have been GT5.
But the point is that the tech make-up of GT5 cannot be improved for GT6, unless they take something out, or downgrade another part to make room. The PS3 is crippled, because it is totally unsuited to handling the amount of alpha that GT5 is trying to push. They are not running alpha with 1/16th size buffers for kicks; they're doing it for a reason. This is not going to change with another GT PS3. That's even before we get to the shadows.
You said yourself that the platform they are using is optimized for Cell/RSX. Well if it is (and there's no reason to assume that it's not) then it's not going to improve, is it. Maybe it's just personal preference, but I would much rather have my next GT experience on hardware that is actually capable of handling what Polyphony are trying to do, because PS3 can't do it. It won't do it tomorrow, next year or in twenty years.
I'm sure it's all the alpha channel's fault, that one step in the rendering pipeline, that one component of a functioning game engine. That's why there aren't any online leaderboards, right?
You seem to be confusing "graphics" with "game".
There must have been "tech issues" with GT3 and GT4, otherwise GT5 would have had nothing to improve upon, technically. 💡
I'm not sure what you're trying to say here. Continuing to model cars and tracks is not "doing nothing"; nor is continuing research into improving the simulation "doing nothing". The logical extension of your argument is seemingly that because PS4 is not announced or set in stone, developers can't do anything.
Surely you must realise how absurd that statement is, as well as being at odds with the fact that in-development hardware frequently changes.
"Modeling" (including physics) is not the sum total of "developing a game". I was going to make the point about "side-projects"; I bet there's stuff cooking over at PD towers that can't even be put into the
next gen, at least not in a fully functioning racing game like GT.
Making the game, then, is putting all the pieces together on a framework
built to run on specific hardware. The latter of which is only possible with the real hardware to hand, or with emulators (bear in mind that the PS3 can be used to emulate a PS1, but not a PS2).
If the hardware "frequently changes" (it's not even been made yet) then no work can be done on that framework. They'll work roughly towards something like it, but until they know exactly what registers and operations units, instructions etc. etc. they have to play with, none of it can be tested and optimised, which is the real meat of the development, especially for a top-tier game like GT. I've no doubt that PD have special hardware they use to prototype new features, or render "in-engine" trailers, but they aren't the hardware we all have.
You still haven't explained why a GT5 with more cars, tracks, racing, customisability, online / social options, game modes etc. is a bad thing. None of that eats into a PS4 game, because it's mostly content / systems that will be carried over or recycled. GT6 on PS3 is but a rest-stop on the same path to PS4-land.