Final Fantasy Versus XIII is currently being put on hold. Nomura, the game's director, said that the majority of the team working on Versus XIII is now helping out on Final Fantasy XIII. The main title in the Fabula Nova Crystallis compilation is top priority at the moment.
While both games will appear at the upcoming August Square Enix party (in non-playable form), Nomura hints at a bigger reveal and more info to come at Tokyo Game Show in October. Knowing Square Enix, this means a minute of ambiguous footage in a closed theater. Let's hope we're wrong about that last speculative statement and see if a playable demo comes in October.