<<While a D400 is a possibility (it is until is isn't as they say), and I have been highly dubious of it ever appearing (in fact my opinion is it will never happen), I would state with the most confidence I have in any projection on this issue that it would have to be cheaper than the D600.>>
I disagree. I have long been posting new threads talking about the possible demise of DX and I have to say I admit that I may have been wrong. In addition, comparing the D600 with a possible D400, is like comparing apples with oranges in my view. Also and against my past feeling, I now believe a D400 may now still be a possibility.
Cost: If it does arrive I would pitch it's price between the cost of a D600 and a D800, in other words a semi-pro DX, not a high level consumer model like the D7100. If those awaiting a D400 want a D800 body + all the functionality + xx fps etc, that's the price they'll pay. I also believe that it would sell very well. World wide there are so many folks almost praying for a D400 and until I bought my D800 I was one of them. However with the D800 lack of fps and despite the 16Mp DX crop it will not perform satisfactorily for many wildlife and sports photographers. Personally I would be unlikely to buy a D400 now as my mix of D7000 and D800 suits me adequately for now at least .
<<BTW as to the link suggesting that Nikon Europe said that Nikon was not meaning to say that the D7100 is the top end DX camera, as I pointed out in another thread, what would you expect Nikon to say - they are still selling the D300s as the top dog in North America. >>
The point here is that Nikon USA said one thing and Europe stated another on their websites.