From the outset, this reads as it may not happen. What form it takes is any ones guess including Fuji it seems..
Fujifilm Will Launch a Medium Format Camera (Top Trusted Japanese Source) :: New Source says it will be presented Photokina! | Fuji Rumors
On the XPro2 thread it was discussed a bit. A Fuji 67 like camera in maybe 645 format would be nice.