Yep I'm in the camp of the D400 believers, particularly with the obvious constrained buffer size of the D7100. With the 51-point f/8 focussing system and a decent 6fps, a great sensor, 1.3 crop-mode, reported excellent video quality, and even live view interpolation said to be better than the D800 for magnified LiveView focus confirmation, the only thing holding back the D7100 as a true DX top-of-the-line is its 1-second buffer capacity. And clearly that was an intentional holdback, as buffer is a very easy thing for Nikon to add. As we know from the D4, Nikon clearly knows how to have a big buffer. So D400 here we come
Now the D700-replacement camp, that is a much tougher one to sort. Or not so tough if Nikon could simply make a D800S with 6fps and 8fps in DX-crop mode with grip. Fps is the one single spec-sheet item where the D800 doesn't exceed the D700 (and the 5Diii). Other than that the D800 exceeds the D700 in every way and there simply is no truth in the argument that 36mp is "too large" for the D700 shooters. The former D700 shooters (and I was one) can get used to it like the rest of us, not that a tough transition at all. Heck according to Moore's law, in 6 months time from now, we will have already have doubled the capacity of our computers and their memory since the original launch of the D800.