Lion will still be OS X, and the next OS after Lion, I don't know we'll just wait and see.
The way I see it is that Apple wants to make the Mac a truly production unit. For example I think they will prefer that when you sit on a mac then you work, developing programs, animation, web sites etc. and when you want to take a break and browse some web site read a book or some articles online you take your iPad.
My opinion is that OS X will not change at it's core but will change in terms of perception and it is a good thing. I always hated that I seem to not be able to concentrate when I stand on my desktop.
For example I start watching an episode of a tv series and after couple o minutes I switch from full screen to windowed and put it in the top right corner and then open the browser and check some web sites. It is this ease of which we can access distractions that Apple wants to change and only by perception not by functionality.
Because ultimately you will still be able to do that but if you want to truly concentrate on something you switch you browser to full screen and it's like you devoted to it completely. Still it's only a perception, not a limitation of functionality.