This is an example of Substance. This is my current logic of where Nikon is probably moving towards.
"$2,400-2,700 is where this (D600) will land. D400 will be around $1,800-2,100."
D7000 MSRP = $1,199.95
D300s MSRP = $1,699.95
D700 Current = $2,199.95
D800 MSRP = $2,999.95
Assume 2 cameras (Nikon has said two more bodies will be released this year D400 over due and now this announcement) between D7000 & D800. 3000-1200 = 1800. 1800/3 (two placements for two bodies) = 600. 600+1200 = 1,800 (D400) + 600 = 2400 (D600). I added a bit since prices seem to be rising as of late with the Yen being stronger to the dollar and normal inflation. The D400 would be a bit more than the D300s, the D600 would be a bit higher than the D700 but a good chunk less than the D800.
Considering what Nikon would be willing to swap out to drop $3000 D800 is what everyone's speculation is. Nikon has been willing to drop the AF motor (in lower DX bodies), smaller view finder coverage (smaller pentaprism), one card slot seems to be realistic options. Nikon is very proud (rightfully) of their new AF & metering systems (D4/D800) so it wouldn't seem they would drop that (especially since the D400 would as well have it- based off of history). So if your dropped the AF motor, a smaller prism, a couple of other features - does that equal $1,000? $1,000 seems too high of a cost of those, $600 seems more realistic as well.
Consider also they probably don't want the price to be equal or under a D400. It makes since they would equally stagger the price (Assuming they will continue with the D400 to match Canon's 7D.) That is how I come up with my pricing.
It could be interesting if it is a 24mp sensor - say from the D3x, which didn't sell well. Maybe the have a glut of sensors left over? And here we thought an entry level sensor would be from the D3s.
If they dumped a FX sensor into a D7000 like body with the same feature set, I think I still would go a D400 with the AF motor, D4/D800 metering and new AF system. Personally that is what I'm looking forward to for an upgrade. If I can't get that, the D3s is still looking good.