Perhaps she could pull it off, but not based on anything she's shown in her work so far (which, to be fair, isn't necessarily her fault). She could do the flirty seductive side of Jean, maybe, but I don't think she's right for the standoffish, serious, dangerous, psychopathic aspects of Jean's character. TBF, I never would have that that Sophie Turner could pull any of that off, either, but she showed signs fairly recently that she really can act.