From my perspective, if Nikon intends for the D7100 to be the new top of the line DX model and replace the D300s, they've missed the boat. Slower frame rate, small buffer, no AF-On button, having scene modes instead of the control buttons will cause me to continue to use my D300s for birds. Hopefully, the headline of the Nikon press release for the D7100 was just unartful wording and there is a D300s follow on in the wings.
"Nothing can be recognized without light and shade. It is only through the eye, the window of the soul, that we can truly understand the complex workings of nature." - Leonardo da Vinci