Re: Please no more prequels!
I dunno. Prequels seem the best route to take at this point. X-Men: The Last Stand dead ended so much, and eliminated so much of the essence of X-Men by killing Cyclops, Xavier, and Jean (the latter of the 3 not being a bad creative decision) as well as depowering Rogue. I get that the cure doesn't seem permanent or whatever, but I think that's a really bad plot point to build a sequel around (making the last movie pointless), and I have my own theories as to why Magneto is still powered.
A future X-Men 4 could have a solid enough roster of characters - Storm, Wolverine, Iceman, Kitty Pryde, Colossus, as well as -possibilities- (albeit not necessarily likely) of returning Angel or Nightcrawler - but the portrayals of some characters (i.e.: Iceman) or the actors of characters (i.e.: Iceman, Colossus) might not be strong enough to build a movie around.
Does Shawn Ashmore have the acting chops to toughen Iceman up a bit, and bring him more in line with his comic book self? Does Daniel Cudmore have the acting chops to portray an actual character, period? These are 2 of my favorite characters from the comics (Colossus more so than Iceman), but the movies didn't do them justice, mischaracterizing one of them (Iceman) and making the other one nothing more than background (Colossus).
If the characters were written well enough, and the acting was strong enough, an X-Men team consisting of Storm, Wolverine, Iceman, Kitty Pryde, and Colossus would be awesome. I don't know what storyline the films would touch on, though.