D4 batteries are of course nice, but then what it will end up is essentually being the the current D4 with a lower 24mp and possibly 6-8 FPS instead of 11 FPS. Nothing wrong with that and a lot of us would like that, but at $6500.00 , I don't think the market at this time would be big enough to entice Nikon to go with it. At some point when technology moves on, we'll probably see a D5 with 24mp and 11 FPS.It should take D4 batteries, have the D4 low-light AF, and fast mirror (= short blackout). $3500 isn't important, $6500 would be fine.
What I think the Nikon market needs now and is asking for (by quite a few) is either a real D700 successor or a true downsized D4 ..both being accomplished in a single body. From a marketing point of view, I think Nikon would have the sales numbers they are looking for if they designed a D800 built body with their latest designed AF system, AF sensors spread out across the frame, 6-7 FPS, maybe a built in vertical grip (or make it optional...whichever the way the market dictates) and a fast processor....and price it around $3500.00 . One could look at it as a D700 successor and others a real downsized revved up D4. A number of markets, both pro and advanced amateur would be addressed. My 1.5 cents.
Dave (D&A)