Actually it is rationalizing based on past behaviour, the only real predictor of future behaviour. In the past Nikon has always kept a pretty sizable financial cushion between the FX and DX lines and they show every intent to keep it that way while offering more financially attractive entry level FX prices.
At least from what I have read, in fact D7000 users ARE clamouring to upgrade to the D7100 - check over at the D7000/D7100 forum.
I recently moved from a D7000 to a D700, depending on the ISO performance of the D7100, I probably would have upgraded to the D7100 (although I am now perfectly happy with the D700).
Of course it is entirely possible I am incorrect, this is just my opinion. So far the only facts we do know is that there is no D400, Nikon has not announced one and no one has any actual idea of when, if ever we will see it.