This is my theory. Cage is introduced as Nick Fury's old buddy from the mean streets of detroit or wherever. That story will be told in a retro story with iron fist set in the late 70's. Cage will be used to surprise attack and muscle the hulk into a vibranium rocket to send him to space and replace him on the team until the final movie when a pissed off hulk returns to a world destroyed by ultron. Obviously the hulk will have a bone to pick with cage. Could this work?