“….and reduce the D300 to a YouTube camera...taking out some still photography features and inserting video.”
I am with John here. What “still photography features” do you think were removed from the D300 in order to add video to the D300s?
I own both cameras and I cannot find anything missing from the D300s. In fact the D300s get 1 more frame per second burst speed. I also prefer separate button for Live View, the improved center button on the multi selector and the latch-less CF card door on the D300s.
I never shoot video but I still prefer to use my D300s over the D300 even though the IQ is identical.
I agree the “D400” is way overdue however I don’t believe that the release of the D300s contributed to the D400 delay.