Rosamund Pike Is Cold As Ice?

According to ForcesofGeek.com, British Actress, Rosamund Pike is auditioning for the role of Emma Frost in "X-Men: First Class" next year. Now, why is she going for the role when, Tahyna Tozzi was cast as her in "X-Men Origins: Wolverine"?

Now surely the studio will just get her back instead of recasting her. Tozzi is 24 years old and Pike is 31 years old. How far from the Wolverine film, is this film gonna be set. I thought that the film will just pick up where the Wolverine film ends.