I used NextStep for a bit when I was a government contractor... It was ok, but the UI, while attractive, seemed somewhat superfluous. But my question is, where exactly will you find NeXT Step in OSX?
You've got "Darwin" at the core, which is a BSD variant, so I was led to believe. You've got the OS X UI at the top, which is very little like NeXT Step's UI (not that I can recall, at any rate. The toolbar that NeXT Step had was nothing like that odd bouncing thing at the bottom of the OS X desktop). The display technology is different...
... I'm not saying NeXT Step isn't there, I'm just saying I don't know where it is, exactly. Is it some kind of middle layer?