Jean is the only character aside from Logan that's so versatile. She has clones, alternate versions, different jeans like full-fledged Phoenix Jean and so on. If they do Inferno,they can easily have Famke there. If they do the future ones where she has Rachel and Hope(I think), it's yet another role for her. It's not taxing to be Jean,so if they have any sense,they'll pimp her out more.