Back in June, during E3, Square Enix revealed that Final Fantasy Versus XIII would actually become Final Fantasy XV. During its announcement trailer the tagline "a world of the Versus epic" appeared at the end of the trailer, which now hints at the possibility of more than just a simple tagline.
During the Future of Final Fantasy event, Hashimoto stated in an interview that Final Fantasy XV is such a large-scale game that many stories may come at a later time. And now it looks like that Square Enix is preparing these Final Fantasy XV stories considering the fact that Square Enix Japan filled a trademark for "A World of the Versus Epic" in Europe (see image below).
Seeing as Square Enix is so focused on doing sequels in recent years, it wouldn't be surprising if Final Fantasy XV had the same treatment. More details about Final Fantasy XV will be revealed at Tokyo Game Show which takes between the 19th and the 22nd of September.