As I wrote over on the other thread:
I know it's rumored that Patrick Stewart did not want to return to a fourth X-Men movie, and therefore, he and Cyclops and Magneto were going to be done in by the Phoenix. (source:AICN) In the comics, Xavier has undergone significant character changes, as have the rest of the X-Men, and if he were to die, the dream would carry on (as it has.) However, the movie-verse is still young. The characters still seem to be adjusting to their powers and the idea that they are hated and feared by "flatscans". As much as I love Storm, the Storm in the movie is far from ready to become the embodiment of Xavier's dream. Neither would have Cyclops been ready to step into Xavier's shoes. I think they will have a loophole somewhere, Xavier's psychic powers will protect him from decimation or atomization or whatever the heck is supposed to happen. I'd have a hard time buying anyone else as mentor in the movies at this point.
As for the emotional connection in the movies, I didn't feel any of the characters seemed particularly tied to one another. Possibly Logan as a protector-figure to Rogue, but I didn't get the impression of anyone's connection to each other. Jean and Scott seemed forced, as did Wolverine and Jean. It was awkward watching them together. Same with Kurt and Storm. Though it was a nice effort, they all appeared disconnected.