Someone should do an MF mirrorless - as a couple of posters have suggested. Both Fuji and Mamiya used to have mirrorless MF film cameras, including interchangeable lens models. Some of the Fujis (at relatively reasonable sizes and weights) even got as big as 6x9 cm negatives!What if Fuji pulled a Pentax, skipped right over a full-frame model and the successor to the X-Pro 1 was medium format? The X-T1 is a very nice top end to the APS-C series, and it is hard to imagine what a 16 MP APS-C successor to the X-Pro 1 could bring to the table that would justify the two years since the original?
What if it wasn't a 16 MP camera at all, but a 50 MP 33x44 mm camera (I'm assuming Fuji isn't going to go backwards to a CCD sensor, and the only MF CMOS is 33x44)? Of course it would need new lenses, but so would a FF successor to the X-Pro 1. I wonder what such a body would cost? I suspect it could be (disruptively) priced right in the realm of a D4s or a 1Dx, giving a real option in that range - the speed of the sports cameras or the image quality of a 50 MP "rangefinder". At present, there is a huge jump in the cost of image-quality focused cameras - from the $2000-$3200 range inhabited by the D810 and A7r up to the $10,000+ territory of medium format - anything in between actually offers reduced image quality at modest ISO (in return for extreme ISO capability and 10+ FPS). What if Fuji (or Sony?) jumped in at $6000 with a 50 MP camera based on the Sony CMOS sensor? It wouldn't have a removable back, but the flange distance would be short enough to attach the entire camera to a tech camera, and it would be reasonably enough priced that there wouldn't be a huge cost argument for back upgrades...