The actor is currently in negotiations to sign on to Captain America 3, which is slated for a May 6, 2016, release. Marvel is counting on Downey to sign so that it can move forward with bringing the Civil War story line into the cinematic universe, a plot that positions Tony Stark (Downey) and Steve Rogers (Chris Evans) on opposite sides of the Superhero Registration Act. Rogers is opposed to the act, which forces people with abilities to reveal their identities to the U.S. government, and eventually forms an underground opposition, pitting the two halves of the Marvel Universe against each other.
Downey would earn approximately $40 million plus backend for appearing in Captain America 3, according to Variety. He would even receive additional money if the film outperforms Captain America: The Winter Soldier.
In September, Downey revealed that there are no plans for Iron Man 4. He can next be seen as Tony Stark in Avengers: Age of Ultron, in theaters on May 1, and is also attached to the third Avengers movie.
How bromantic! See Supernatural's Sam and Dean hug it out (a lot):