Here's my take on it: the DF will be the most successful Nikon FF camera to date.
Forget the 'Retro" label, that's just Nikon trying to avoid eating humble pie over it's years of dreadful design. The DF isn't going to be that different to a 6D apart from the addition of a physical shutter speed dial. OK, maybe no video, so what ? Of all the people I know who have dslrs and are not specifically videographers or movie makers, non have used the video function after the initial 'wow look at this fantastic quality video' effect has worn off, and they revert back to the camcorder that is much more suited to video of the kids.
I always said that ever since Nikon changed the logo to make it look as if it had had one too many, Nikon lost the plot with their cameras, trying to have all bases covered to suit anybody and everybody. They've finally realised that the vast majority of FF users do not want pop up flash, they want sound ergonomics in a sensibly sized quality body, producing the highest possible perceived IQ, and a 16 mp sensor is going to work just great for that. They want a crystal clear OVF with no translucent LCD murking the image up which Nikon have been doing for years, and even Canon joined that game with the 5D3 and 7D. ( Yes wait for the 5D4, it will loose the translucent crap and have interchangeable screens ). If Nikon are talking about 'pure' photography I can't see this camera having a hybrid viewfinder as this must reduce the OVF quality.
Price wise I guess this will be more expensive than the D610 ( or maybe it will be the D620 by the time the DF is launched ) as it will be a higher quality product, made in Japan instead of farmed out to cheaper countries as so much of the rest of Nikon gear is.
If Nikon have finally managed to get their designs back on track they may have something worth having, like the original FM, at the time of its introduction called 'the worst Nikon ever' by some trade press, yet went on the become the most enduring designed slr in the history of cameras.
Here's a shot of mine. It was the first camera I ever bought new, and despite the fact that I went on the use FM2, FE2 and F3s I never had the heart to sell this one !