Final Fantasy Versus XIII became Final Fantasy XV two years ago, according to an Edge interview with Tetsuya Nomura.
“As you may know, [seven] years ago we announced three titles, Agito, Versus XIII and XIII, but one to two years after that announcement in the company we started discussing the possibility of moving Versus XIII into XV because of the size and scale of Versus XIII,” he said. “So we were warming up the idea of considering the move to XV – which is the mainstream [entry of the] Final Fantasy series – and between that time and now we had several chances to announce updates of the series and we debated if we should go with Versus XIII or announce the change to XV.
“About two years ago we confirmed, internally, that we would change the title to XV and then at the same time, around that time, the company started working on next-gen consoles. So that became a really good trigger to move on to the change of XV.”
Nomura also confirmed that the name change occurred around the same Final Fantasy Agito XIII saw its name change to Final Fantasy Type-0 – a move that took place due to the game’s “lack of connection” the original FFXIII vision. Perhaps the same can now be said for XV, although Nomura assures fans that the original story and concepts have not changed despite shifts to new platforms and mainline FF status.