Lightning Returns closes the book on the Final Fantasy 13 trilogy, bringing it all to a satisfying conclusion. But we might not have seen the last of Lightning herself, as director Motomu Toriyama says her popularity may well lead to some cameos.
"For Lightning, her story ends here in Lightning Returns: Final Fantasy XIII, as this game is meant as a finale to this series," Toriyama told Siliconera. "But we know that Lightning is an extremely popular character, even when compared to other Final Fantasy characters. So there is a possibility that Lightning would appear in other future Final Fantasy titles, not as a protagonist, but as a guest character."
Whatever appearances she might make, it probably won't be tied into the story. More likely the guest spots would be crossovers like her appearance in Final Fantasy 14, or the Cloud costume making an appearance in Lightning Returns.