Apparently Sony is helping Square Enix develop the game in exchange for exclusivity.
VGLeaks has posted an interesting rumour, which comes off the heels of earlier claims they made regarding Final Fantasy Versus XIII. Apparently, with the problems that Square-Enix has had with current generation consoles, the relative lateness of Final Fantasy X HD and the absence of any other adaptations (not to mention the failure of Final Fantasy XIV), the company has shifted development of Final Fantasy Versus XIII over to the PS4.
And not just that, but this development was halted two years ago before Sony got involved and started co-developing it so it would remain exclusive to the PS4 (similar to how Versus XIII was to be exclusive to PS3). The game apparently is now called Final Fantasy XV, and Sony is currently helping Square Enix with FFXV assets along with everything else.
On the surface, it’s just a rumour and should be taken with a grain of salt. However, it’s interesting to note that the first gameplay trailer for Versus XIII was shown two years ago before development was then halted. Also, this.
Wait till E3 2013, we suppose.