Well It depends If they want to explore It more.Mystique and Beast may not have much Interaction In DOFP untill X_Men VS Brotherhood showdown and even then It's possable Mystique may fill void Destiny had In original comic and 1990's show gave Mystique to kill
target of assassination.
DOFP could be structure as 3 ways 1:Future 2
ast with X-Men and 3:Past with Brotherhood.Time travel connects 1 and 2 together and the X-men trying to prevent assassination connects all 3.
I personally feel It would be a backtrack to have Mystique for any reason run back to mansion.I am hoping to see more devolpment away from acting like teenager and closer to Trilogy version.There Is some great character devolpment that can come In that
devolpment and Jennifer would do great at It.