3. Time Travel
Time travel is a key aspect of the Age of Ultron comic book arc, with Nick Fury and Wolverine using opposing methods to bring Ultron's rule to an end. Both of their methods involve time travel, of course, with Nick Fury intending to launch a surprise attack on Ultron himself in the past and Wolverine taking the somewhat harsher action in intending to kill Utron's creator - Hank Pym - before he gets the chance to bring Ultron in to existence. Aside from time travel, what their methods have in common is the means in which they travel through time; they use Doctor Doom's time platform. Of course, Doctor Doom is not a part of the Marvel cinematic universe but, if our predictions are correct, a certain Time Gem (or the Marvel cinematic universe "Infinity Stone" equivalent) will be appearing in the Captain America sequel - Captain America: The Winter Soldier (which comes out in less than three months). The Time Gem should afford the Avengers and/or Nick Fury the opportunity to travel back in time, should they wish, to stop Ultron before he starts, so to speak (using whichever potentially conflicting methods they choose). And, given that time travel is such a prominent and focal part of the comic book arc, it definitely should happen in the movie.