Update Ultron’s origins: Since Ant-Man doesn’t come out until after Age of Ultron and features Scott Lang, Hank Pym probably isn’t going to be the inventor of Ultron. Instead he will be invented by Tony Stark, S.H.I.E.L.D, or both. A throw-away line referencing Hank Pym being Ultrons inventor, such as “Hank Pym came up with this forty-seven years ago”, would also link to Ant-Man.
Wakanda and other locations: Age of Ultron is confirmed to feature multiple location around the world and even filmed in a location in Africa, so why not show a scene of Wakanda. Presumably Ultron’s plan to save humanity from itself will reach beyond America so a scene showing Ultron Drones marching upon Wakanda, and other locations, would show the grandeur of Ultron’s attack and provide fans with a wonderful plethora of Easter eggs. Other locations which could be Easter eggs during this scene include; Hell’s Kitchen, London and Attilan.
The Netflix shows: Marvel needs to hype up its new shows, especially Daredevil, so a reference or two Newspaper articles or internet articles about Fisk Industries and/or one of Matt Murdoch’s cases and a Heroes for Hire advertisement would be a good idea.
Ultron to kill an Avenger (And they stay dead): There are several reason why Ultron should kill an Avenger. One; It will establish Ultron’s character and the serious threat he poses to the Avengers and the world. Two; It will keep the film fresh in a genre where films aren’t brave enough to kill main characters. Three; the Avengers are getting pretty crowded, and if Marvel wants to introduce Quicksilver, Scarlet Witch, Doctor Strange, Captain Marvel and Black Panther to the ranks, characters are going to have to die. I imagine Captain America, Hawkeye of Iron Man to be the late Avenger.
Doctor Strange revealed in mid or post-credit scene: Doctor Strange is one of Marvel’s most anticipated movies and with the casting of Joaquin Phoenix all but confirmed a character reveal is in order. Wong enters the loft of the Sanctum Sanctorum, briefly looks up, and continues on with his chores. The camera rises to reveal a levitating and meditating Doctor Strange. By showing Doctor Strange meditating it is hinted that his astral form is off on some other-worldly business, explaining his absence of Age of Ultron.