According to some new whispers from dark corners of the internet, we may now have a reason for Final Fantasy Versus XIII's massive delay: it's now being developed as a PS4 title with a brand new name.
VGleaks (who've proved themselves to be a relatively reliable source of news over the last few months) claim that Square Enix halted development of Versus XIII two years ago, in order to turn it into a dedicated PS4 exclusive. Sony have reportedly jumped on board as a c0-developer, with a view to making the newly renamed 'Final Fantasy XV' as shiny as possible.
Square Enix are certainly working on something PS4-related, as evidenced by their embarrassingly pointless appearance during the New York reveal. Could it be Versus XIII?
This ties in with the latest official line from Square president Yoichi Wada, who claimed that Versus XIII is still in development (and will "knock you off your feet"), and also with the rumours that it was secretly cancelled. We'll doubtlessly find out more in the Summer.