Rogue HAS to gain her comic powers somehow. There's limits as to what she can do with her current powers and they've been explored enough in the 3 movies. I think the best way to go is have her accidentally hold on to someone for too long. Have some random mutant, with flight and strength abilities attack Rogue and maybe have him make contact with her skin for too long and she can't stop him so she unwillingly gains his powers.
Rogue will not be back for X4.
I admit this with the heaviest heart, being the unrequieted love slave of Anna Paquin. But the fact is, they ended her arc (and I say this in the loosest of terms; they actually
terminated any arc she had).
Same with Cyclops; he will not be back.
Yeah, "scheduling issues" have been cited in both cases, but I know in my heart that's not even the tip of the iceberg. Bryan Singer had Kevin Spacey for (I don't remember the exact timeframe) a
very brief amount of time, yet his Lex is very prominent in the film.
Both Rogue and Cyclops were clearly and simply deemed not important enough for X3, despite being (logically) the two
most important characters linked to the film's themes - the cure and Phoenix, respectively.
Thus, logic dictates that if these two characters weren't considered important enough for the storylines they could've served the greatest in, it's highly doubtful they'll feature prominently (or at all) in any sequels.
Plus, from a simply creative perspective, bringing back Rogue (repowering her) and Cyclops (resurrecting him) is sloppy retconning. If Fox wants
X-Men: The Last Stand to have any historical and artistic relevance (I'm laughing as I type this, but I'm trying to remain objective) they cannot
undo in X4 what they did in X3. It's public admission of "we screwed up!" and leaves the audience wondering "if things just revert back to normal, why did I bother even watching X3?" No, they've dug their graves. They have to move on (I wish they wouldn't, but they should).