Fujifilm X-T1 vs Nikon Df - Verdict
Once again, both the Nikon Df and Fujifilm X-T1 are great cameras and I'm sure each will prove to be very popular with enthusiast photographers. But for those looking for a retro shooting experience akin to that of film SLR of yore, the preference would be the X-T1.
The size and shape of the Fuji camera are closer than the Nikon Df to those of a film SLR, and anyone who likes to manually focus will love the split-image focusing. Plus, the fact that the X-T1's colour modes are based on classic Fuji films, such as Provia and Velvia, will also resonate with photographers.
As for the larger question about producing a digital camera that behaves like a film SLR, I think the problem may resolve itself when screen technology improves to an extent that the panels can be thinner. Shaving a couple of millimetres off of the camera body can make a big difference.
Alternatively, by removing the rear LCD screen completely, a digital camera DSLR could be a lot smaller in height and in depth.
Obviously this would make it much harder to change settings or review images, but perhaps if there was a hybrid optical/digital viewfinder, like in the Fujifilm X-Pro1, then this could become a possibility.