Like John, I still think a D400 is likely, the D7000 is a great camera but still lacks features that a pro DX shooter like wedding photographers or serious wildlife photogs would want.
Nikon has 3 consumer cameras all upgraded within the last year. They have 4 prosumer and pro cameras 3s, 3x, 700, and 300s all due for an upgrade. Not impossible to see at least 3 of these upgraded in 2012.
Last Africa trip I did all pros and semi pros had pro FX cameras (1D/D3). And why would a pro wedding photographer need a DX? Viewfinder still rocks on FX. Especially if you're shooting all day.
It doesnt have to make sense photographically. It's only about 1 thing, money. Development costs and production costs versus sales and profit margins. With P&S cameras getting better and better, Im sure the SLR market is feeling some pressure. So if you had to cut costs somewhere, I think a higher-end DX camera would be it. Most pros would get a D4. There is no way Nikon would not make a D4. But not all pros can afford or need a D4, so a cheaper FX would also be necessary, the D800. That's also the goto market for all gadget geeks that want an SLR, because 'FX is better'. (i cant count the amount of time ive heard that, and thats like a self fulfilling prophecy).
Then they need a product for 'almost everyone else'. Thats the D3100/D5100 entry market.
The D7000 was kind of a weird camera in the whole chain. Even the reviews agreed on that when it came out. It's a remarkably excellent camera for a relatively low price. It even feels pro-ish. Image quality is probably the best of all Nikon cameras right now (including D3), it's got 2 card slots, good focus, etc etc. The only gripe I have so far using it in some circumstances is the limited buffer. The D7000 has been an excellent seller for Nikon.
I just dont see economical room for a D400. What sufficiently large market would buy it over the D7000? A few underwater photographers that prefer DX for macro and still want a 'better' camera? If I ran Nikon and Id have to cut costs, thats the first SLR id scrap.
But, at the same time I see your points, and I hope Nikon does make one, because the more choice as a consumer the better.
Cor