And the others were positively minuscule... wait a minute?
The main thing is, Versus XIII had an engine made specifically for it, and they've said they intend to make KH3 on that engine. And that's all being done on the PS3. Putting it anywhere else will have a negative effect on quality or release time [if not both].
Medaka Box. -- When your reality isn't crazy enough. If you read manga, read it.