An announcement could be coming from Square Enix in the near future because, in the last few hours, the Japanese company registered a trademark in Europe. The new trademark relates to something called "Warrior of Despair" - which could very well be a new project.
When trademarks are secured like this, it often means that an announcement of some kind is on the way. In this case, it's unclear whether we're looking at a brand new IP or a subtitle for a game in a pre-existing franchise. Either way, it seems as though that the Japanese company will have something to reveal at some point.
Perhaps Warrior of Despair has something to do with Mobius Final Fantasy, since there was a Sephirot skin called Hero of Despair; a theory suggested by AllGamesDelta. We hope to find out soon and will update you in due course.