Fuji's SLR could take, I believe, 6x6, 6x7, 6x8 or 6x9 backs. In rangefinders they also made 6x7, 6x8, and 6x9. I have a 6x7 and 6x9, and they're great cameras. Unfortunately they kept the 6x8 rangefinders out the USA market.
This is probably a one-off prototype camera, similar in concept to the futuristic cars at the auto shows, that are designed to gauge public acceptance. If they get thousands of people sending them deposits for the cameras, maybe they will eventually be produced. And maybe not. Just a thought.