1: I'm not quite middle aged yet, but I also have a soft spot for the 2D animation I grew up watching. However, I have also played computer games for almost as long as I've watched animation which has exposed me to 3D/CGI cut-scenes for quite a while, so I don't really have a preference for one over the other.
2: In mainstream films, yes. However software like Flash has put 2D animation back in the bedroom and helps keep a very strong amateur scene going.
3: Do you mean 3D artists or 3D animators? While perhaps not essential, a 3D artist will always benefit from 2D art skills. Less so in animation because the animation processes are so different.
Good luck with the dissertaion.