The only good trilogy i watched was LOTR. The success was unbelievable.
To tell you the truth, i do not see the X-men trilogy making it to the tops.
I am not a fan of Storm's character, and it's not like she had any essential role in both movies, therefore i won't be surprised if she won't appear in X3.
But then again, maybe giving her a bigger role in the upcoming movie will be kind of good, if not marvelous, for the story line and the movie in whole.
Gambit, on the other hand, is one of my favorite characters. But finding the Gambit of the comic books is not an easy job. Marvel have done a lot to make Gambit's character as outstanding and rare as possible.
In the comic books, Gambit and storm share a special bond, and i think that it's either both of them appearing in the movie, either none.
Otherwise it won't make sense and the movie will take a huge turn towards confusion and complicated storyline.
As for Wolverine (who is my second of the two personal favorites), he did have great roles in both of the movies so far, and as you can see, that's what people like.
As much as i adore him, i wouldn't mind seeing a change in the plot in which Wolverine doesn't have the leading role.
But if the rumors are true, and the movie is going to focus on Phoenix, then i guess both Wolverine and Scott will have important roles in the movie.
But then again, that is only one's opinion.