3. The Mid-Credit Scene May Introduce New Characters
Though it's known that Age of Ultron only contains one additional stinger once the credits roll, little is known about exactly what it might be. There's a pretty damn strong chance it'll sow some seeds for Civil War, and what better way to do that than by introducing at least one new character who will appear in the movie? Black Panther is of course an easy bet, then there's the movie's villains, Baron Zemo and a returning Brock Rumlow/Crossbones, who likely need to be established quickly given how much will be going on during Civil War. Either way, this is a pretty crucial mid-credits scene as it has the responsibility of setting up Civil War, something which likely won't be left to Ant-Man, and Marvel surely won't waste it on a throwaway scene. Expect something big.