D400..Waiting for new sensor technology?

Personally, I think Nikon had to make a tough choice in the wake of the tsunami in Japan (where the D400 would have been designed) and the flooding in Thailand (where the D400 would have been produced).

I think they had limited resources and had to choose something to delay. They kept the D4/D800 for the Olympics, leadership and profit, and the D3200/D600 for revenue. The D400 will be late (hopefully). It is possible they'll skip it, but the pricing of the D600 seems to leave room for it, especially since they dropped the price of the D7000.