Yeah I can't stand when they change casts either. I only hope they just leave out those characters. I mean, come on, characters are always coming and going in the comics, why not in the movies as well? It doesn't need Storm or Rogue or Cyclops...ok, maybe Cyclops would be important for a Phoenix story, but there might still be time for Marsden to come back.
Singer's going to be missed. I would have rather seen an X3 with Singer than a new Superman movie. But I think Vaughn'll do a fine job.
The one bright side, though, it sounds like Singer's ability to get the Superman flick off the ground might finally break the ground for the Superman Vs. Batman flick that's been in the pipeline. When asked recently if he'd be willing to play Batman again, Christian Bale supposedly replied, "Two more actually, and then Brandon Routh, the new Superman, and I, are doing Batman vs. Superman as a movie." The idea for a Bats vs. Supes movie has been around for a while. Apparently there's a great script written for it by Andrew Kevin Walker (Se7en, Sleepy Hollow). It was all set to be directed by Wolfgang Peterson, but he opted out when they couldn't find anyone to direct or play the next Superman.