2. He'll Become The Avengers' New Leader
In the comic books, despite the common consensus that he has been, Doctor Strange hasn't actually been a member of the main Avengers team at all. He has worked alongside the main Avengers team and has been a member of the New Avengers, but he's never been on the roster of the flagship team. That will definitely not be the case in the Marvel Cinematic Universe and, given that Captain America is likely to die in Civil War, Strange may well be approached by what will then be a re-established S.H.I.E.L.D. to lead the team against coming threats. Strange was already on HYDRA's radar back in Captain America: The Winter Soldier - and that means he's known to S.H.I.E.L.D. - and, after the catastrophic events that will occur in Civil War, the team will need a calming head to lead. Strange could be that man and the seeds may well be planted for that to be the case in his own movie.