That was another rumour, it is still called Final Fantasy Versus XIII.
Just a demo. Nothing more.
However, with SE releasing more and more information and news regarding the future of Agni's Philosophy, I'm starting to doubt that.
...
Versus hasn't been released because SE has horrible management. Think about it, if SE had proper management, FFXIII wouldn't have turned out to be a mess (w/ all those late player testings and staff departing), Type-0 and Versus could have been released, and at the very least KH3 and a sequel to XIII would come right along.
I've heard SE say stuff like 'The closer a game is to its release date, the more updates and news it will receive'. Also, SE isn't interested in releasing news for Versus, mainly because it proves to overshadow other games recently announced or nearing their release date, such as LR:XIII.
That's probably why we're not hearing from Versus much.