If you wait, you'll find that the D400 is going to be amazing. It will also compel you to wonder what the D500 and D8000 will be like. I won't speculate as to what it will look like. I know I would have missed pretty badly on the D7k.
The D4 is highly unlikely to arrive before late next summer, and more likely in the fall, if the "cycles of products" timing is to be believed. On the other hand, there are literally thousands of details associated with designing, manufacturing, marketing and selling these things that could cause things to move one way or another. (Nearly always these take the form of "the X thingie does not work yet, and we will need another Y months to complete it, and it will even take Z months to remove it entirely.")
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!