Yesterday I talked about some thoughts on the possible D700 replacement, today I'm going to discuss the D90 and it's replacement. Again this is a combination of rumors and personal thoughts.
Other possible specs are uncertain at this this time, but I'm going to guess that we'll see an improved frame rate, maybe 5FPS burst. The D8000 could follow in the T2i/550D footsteps and have a 3.2" 3:2 ratio high resolution LCD screen. The advantage of the 3:2 ratio screen is clearly seen on the T2i, no black lines around your image, the enter screen is used to show the image. The body design of the D8000 could also be different than the current D90, which has a heritage leading back to the D70 and D50 designs of 6 years ago. That possible redesign could be due to the in the size and ratio of the rear LCD.
There is also some talk of this new camera not having the built in focus motor. That would drop one of the incentives to pick the higher end models like the D90, but Nikon is moving to replace the remaining non-AF-S lenses in the next few years so that may not even matter, unless you have a bunch of older AF-D lenses. In some ways I can see Nikon pulling the AF motor from the D90 replacement in order to maintain sales of the D300s, which may very well be out specd by the new camera. Such a development could lead to some very angry D300s users, but that is how the industry works. When it came out the D90 had some features the D300 did not and it didn't hurt sales too much then. Of course if the D90 replacement has higher resolution that could be a tricky situation. Maybe we'll see a D300x/D400 with higher resolution sooner than two years as per the normal cycle? It has long been speculated the D300s was just a stop gap measure to bring video and some new features to the D300 in order to maintain sales.
Another area of interest is what will happen to the kit lens that ships with the D90? Will Nikon introduce yet another 18-xxx lens or will the 18-105mm VR be the first kit lens other than the 18-55mm to last more than one generation? Some have said that a 18-135mm VR is possible, but I think it is more likely that Nikon will retain the 18-105mm VR, which provides ample coverage for a starter kit lens.