The newly announced Final Fantasy XV looks like a big game. It could even be big even for a successive title—something like a Final Fantasy XV-2, if you like. Perhaps!
In various forms, the game has been in development for a long time. And when speaking with Famitsu.com, Final Fantasy XV game designer Tetsuya Nomura acknowledged that the trailer did say, "the world has changed", which provided an appropriate segue for the game's title change. (Originally, Final Fantasy XV was titled Final Fantasy Versus XIII.)