Honestly I'd be a little surprised if this was real. There are several reasons for this. The first is that the picture we've seen would be incredibly easy to fake, hell I could make that. The second is that XII wasn't exactly the most popular in the series, so a sequel to that over a remake or sequel to the more popular titles seems odd. The 3rd is simple, Squenix have moved on. They already made 2 XIII games and a type-0, are still working on Versus and have other projects as well, it just seems unlikely that they would go back to make another sequel to one of their least popular series.
Don't get me wrong, I really wanted to love XII (but various things got in the way), it's just that it wasn't as good as it could have been and it's popularity among fans reflects that.
Having said that, a proper sequel that fixed the various retardations of XII (and with absolutely no story based DLC) could actually be very awesome.
Eh, you don't have to love the main game...But you can love the world its set in
Thanks to Galadin for the awesome signatures