Originally Posted by
Glio
Because of the experience I have of meeting people who enter modern X-Men with Astonishing, it really isn't that problematic.
Kitty Pryde in the collective imagination is like an eternal teenager, introducing her as an adult who returns to the X-Men after time out can serve as a hook. She is like the audience, grew up with the X-Men and returns now.
Colossus and Breakworld can be replaced by any resurrection in reality. In the case of the comic, people are used to seeing mutant resurrections all the time. In the case of movies, it may be another case like Kitty.
As with Kitty, the audience has become accustomed to waiting for Jean already dead. It is hard but it is true. The status quo of "Dead Jean, Cyclops with new girlfriend and resentful Logan" is very easy to understand.
Cassandra in cinematographic language can be replaced by any villain with telepathy. As Mr. Sinister, for example.