In a interview with Amateurphotographer, Fujifilm's operations manager Hiroshi Kawahara said that the company is looking into the possibility of a full frame mirrorless camera. With the exception of some wide angle models, the current XF lenses are designed to cover a full frame sensor:
"Fujifilm technicians are seriously investigating the possible launch of a full-frame compact system camera (CSC) and are focusing on the sensor and processor that would be required.
Kawahara confirmed that the covering circle of Fuji's current X-series lenses is large enough to accommodate full frame. But he accepted that some current, wider, focal-length lenses would not be fully compatible with full-frame and that this risks alienating existing users."