Pike would be the perfect Emma Frost, though. (A Google search reveals so many photos of her in revealing white dresses that it's like she's been screen-testing for years.) Naturally, I do have to nitpick and ask what Emma would be doing in First Class. Emma was originally a villain wrapped up in the Dark Phoenix Saga, but she later sought redemption by joining the X-Men. They mistrusted her past, her saucy outfits, and her blatant "Cheat on Jean Grey!" overtures to Cyclops, but it all worked out.
Obviously, she's much younger than Magneto or Professor X, whose origins will be the focus of First Class. However, we know what Fox thinks of X-Men mythology. The fact that they bragged about including Emma in X-Men Origins: Wolverine won't matter any more than the books. (There she was the 20-something, improbably blonde sister of Wolverine's girlfriend, Silver Fox.) Will Emma be a student, a love interest, or an adversary of Erik Lensherr and Charles Xavier, primed for a spin-off of her own? Will she be in it at all? We'll see.