storm may be have the most potential, but the focus will mostly be on showing the extreme nature of phoenix's powers. it just makes the most sense for that to be in the movie. i dont see why they would just up and make storm 18X more powerful than she ever was in the movieverse. she can fly now, thats something new, i dont think they are gonna overload her with power all at once.
having said that, i think that rogue may be doing some very cool stuff. the battle will probably be near the end of the movie, and throughout the movie we will see rogue conflicted with the cure issue. it will be sort of a surprise when rogue shows up in the battle, because it will be after we are led to think she went for the cure. it will be like TA-DA! rogues here. she will probably have some amazing display of power even if its just for that scene to show shes back in action. during this scene she may steal multiple abilities at a time (ie. stealing juggernauts strength, using it to punch arclight across the screen, which in turn steals arclights power etc...) giving fanboys a taste of the comicbook rogue (maybe she will even fly)
anyway, if you think of it like this, it becomes clear why she wasnt in the lineup on the trailer, they want it to surprise you to some extent. i think they will use that opportunity to give her a great scene that will leave us comic bookers creaming our collective levi's.