I'm betting the D400 would represent some significant additional features over the D7000 although I'm not certain exactly what they'd be. Further I can't see the D400 coming out anytime soon.

The price point difference between the D300 and D7000 is fairly significant so Nikon obviously has to make some move but is the technology there to really make a sufficient upgrade to a D400 given the new features set of the D7000? I doubt it at present but who knows what technology will be affordable and available six months or a year from now?

Best guess, and it's a sheer guesstimate is that we won't see a D400 for at least a year. In the interim the D7000 will likely sell well to those upgrading and to new users although at its price point the attraction to new users won't run as high as the D90 has IMHO.

I'm not upgrading from my D90 (and two D70s) to the D7000 and suspect the next upgrade will be the D7000's upgrade or the D400 and not before.

Am glad to see your patience and I don't think it's misplaced.