I think in this case all the camera makers have similar issues, not just Nikon. From my own experience I would say most of the newer lenses are still good, perhaps can take challenge from even more mega pixels sensor. The problem is, IMHO, may be in a little more limited useful range of f stops. Modern technology has made most of the popular lens makers capable of delivering good and similar quality lenses, Nikon is not worse and may be not better than others. More mega pixels will still deliver larger picture file, which if necessary - gives more room and detail for retouch, and in such case, let's say you capture an image with D800 and scale it down to D700 size, will still give visible better result than original from later. I continue to welcome high mega pixels, but honestly speaking, I think the digital camera until D700 and 5DII has reached the requirement of 90% of still needs, however, world does not stop then.
Pingang