Whoever is posting these rumours obviously never plays games themselves, else they'd have the sense to avoid stupid hyperbole.
GT4P was a mess visually and content vise, popup galore, and performance was far from perfect as well, and it dropped online it promised completely. But hey if the rumour monger never saw it - or choses to forget to sound more controversial, it's all good right?
Hell even GT3 had 2-3 completely unfinished stages in there (I'm talking GT2000 visual level, with popup that PS1 games would be proud of), and that was a very polished, complete game.
PD games always had fantastic production values, but they were never shy to add things until last minute at expense of polish in some cases, but of course it all sounds better to talk how Sony is pressuring them Now, since the 'PS3 is dying' and all that stuff.