Fabula Nova Crystallis & a decade of Final Fantasy XIII: an interview with producer Yoshinori Kitase
"In the mythos, there are various gods and settings that are within that storyline. But in terms of the XIII series that pertains to Lightning, that world will definitely come to an end. But the overall Fabula Nova Crystallis, they are the backbone of games like Type-0 and Final Fantasy XV. We don't believe Fabula Nova Crystallis will end with Lightning Returns. Fabula Nova Crystallis is still existing."