No Storm,please.
If the rumours are true,they already have moira, emma,mystique and jean.
If they include Storm, that will be way too many female characters in the movie.
Anyway,Storm is always a non-factor, if you ask me.
She doesn't contribute anything to the plot or narration of the movie.
And frankly speaking,Storm is one of those mutants that doesn't have any interesting
storylines.
If I can recall,the only thing I can remember about Storm is she is claustophobic, her battle with Calisto to be leader of Morlocks and that one time, she was under Sauron's spell and she totally went nuts and crazy during an episode of "Savage Island" from the 90s cartoon series.
Other than that, I don't think there's anything remotely interesting about Storm,oh yeah..... her brief affair with Forge but I don't think Forge is even going to be in First Class so that cancels it out completedly.
Bottomline: Storm is cool cause she has awesome powers, and if anything,the reason to have her in First Class is just a lame excuse to see special effects such as lightning/thunder and cool battle/fight scenes in the movie.
But other than that, she don't really bring much to the table in terms of driving the plot/narration of the movie.