My D200 still works OK, but I don´t really use it due to IMO poor performance compared to the D700. I decided however to use it for some documentation work a month ago, as a kind of "ten year anniversary"! It did the job I suppose. Images were used in my report. But where it really loses compared to the D700 is images of soil profiles.
For me, the D200 became obsolete the same moment I got the D700 back in the summer of 2008, at the age of two (got it May 2006)!
The D700 on the other hand, 8 years old now, I do not think of as obsolete, and still use a lot, since it is very much "good enough" for what I do. But of course, when I want the best possible image, the D800E is a little (sometimes a lot) nicer, especially when printing large...
From now on my D200 will probably just be used for sensor cleaning training!
/Johan