Originally Posted by Raiden
I just found it hard to believe that with tons of characters already planned in DOFP, that Singer would shoehorn Magneto's son in there anyway. It feels to me like it was done deliberately and almost like a last minute move.
And before the Quicksilver's announcement, it seemed like the Brotherhood in the 70s will just consist of Magneto/Mystique. Its not hard to believe that they would want to include more Brotherhood members in the movie if Quicksilver really ends up a member of the Brotherhood, especially majority of the film will take place in 1973.