Andriasang reports that Square-Enix will announce details concerning future Final Fantasy XIII products on September 1st during a Final Fantasy 25th anniversary event in Shibuya, Japan. The stage is called “Final Fantasy XIII Lightning Saga: New Developments Presentation.”
Presumably, Square-Enix would announce Final Fantasy XIII-3 to pick up where Final Fantasy XIII-2 and it’s downloadable content left off.
Square-Enix knows you want more Final Fantasy XIII and not Versus XIII.