I'll not bring up hypotheticals more than go with what I know about the Playstation 3 and Gran Turismo 5.
The only reason I would see PD setting up the successor for the next Playstation would be Sony making a console which properly utilizes current electronic knowledge. From what I can tell with the PS3, they're going for graphics to the point they are not compensating for the side effects of such a huge push toward graphics capabilities, and, as with most mainstream gaming system providers, making the box look real neat and stuff.
To elaborate on side effects of huge pushes for graphics, my Super Slim is going to need a significant modification to easily vent out the heat it produces when playing Gran Turismo 5. Only when my room is a little chilled and I have a large fan blowing across the path of the vent is it not prone to gradual overheat symptoms. And, of course, the loading times can get to be long enough I can step away to make an instant dinner, return to my seat to game, and still be loading, depending on the internal heat of my console.
Unless PD is given a sort of pay from Sony for producing for the PS4 (I doubt something like this is really done in the gaming industry, but who knows what shenanigans those financial heads are up to), rather than PS3, or the PS4 turns to have... MODERN loading times, at least, and decent ventilation, then PD has no real reason to hop up to the next generation console.