From Gadget Lab from Wired.com:
But will we see a D700-level camera with video? To compete with Canon, the answer would have to be “yes”. But as the D700 currently shares the exact same image chain as the flagship D3, the whole lineup would have to change. This would make the camera more expensive (Nikon likes to share electronics and even body-shells between different models to bring down costs). This makes it seem like the answer is “no”.
More likely is a D400 with 1080p video, which is exactly the guess that Digital Rev is making. It would also get a 16-18 MP sensor, although in smaller DX-dimensions. To us this seems plausible.