At this point I see no reason to believe that Nikon has any plans to expand the pro or pro-sumer DX line.
And at this point I don't know what to do about it. I need to upgrade from my D200 but Nikon has nothing that would serve as a reasonable upgrade to a D200 level body given that the D300, though very capable, is quite long in the tooth already.
Not sure what Canon has to offer. I'm such a long time, die hard Nikon guy I can hardly bear to look. But that is not going to last too much longer.