Canon was very slow to market with a replacement for the EOS 7D, but ended up making a very good camera in the end with the EOS 7D Mark II.
Nikon on the other hand is still without a modern, flagship, APS-C camera. The D300 was announced in 2007, and the D300s refresh was in 2009. So will we ever see a Nikon D400? Or will Nikon continue to focus on full frame cameras and the entry level APS-C market?
Thom Hogan seems to think so:
I’m hearing the D400 prototype rumors again with the goal of a fall launch, yet the list of features hasn’t seemed to change a lot. Sure, 24mp, 8-10 fps, and higher video specifications. But despite another whole generation of cameras passing by between the prototypes, the end point didn’t seem to change much, as many of the same features are being mentioned again.
Thom has done a nice article about what to expect in the D400, whenever it does make it to market. A lot of what has been written in the past has appeared in other Nikon DSLR bodies, full frame and APS-C alike.