I personally believe that the PS4 will either get announced either at this years E3 or next years one by Sony. What with the Wii U coming out later this year and Microsoft most likely to announce thier new X-Box console at E3 too.
Plus the PS3 is coming to the end of its life cycle. It has been out for around six years irrc.
It makes no sense for SE to announce and release the game for a dying console.
Plus if it was gonna be a PS3 game, don't ya think that SE would have announced it already.
The fact that they aint done this means, I suspect that they will most likely announce that KH3 will be coming out for the PS4 imo.
This is actually possible I guess. And wow, I know SE has been slow with releases (hello Versus!) but a major title missing an entire console generation really drives that point home. I'm probably better off just waiting to get Alzheimer's and playing the first game over and over like it was new. That's probably the faster option.