Well that certainly escalated quickly: over the last couple of weeks Robert Downey Jr. has played rather coy about what's next for Tony Stark and Iron Man in the Marvel Cinematic Universe, but now it looks like we know the answer, as he's just been recruited for 'Captain America 3,' in a storyline that's said to bring Marvel's Civil War arc to the big screen -- which is a rather huge development.

Variety reports that Downey Jr. is in the final negotiation stages to reprise his role as Stark/Iron Man for the third 'Captain America' installment, which is set for a May 6, 2016 release. 'Captain America 3' will bring the Civil War storyline from the comics to the big screen, which will kick off a new phase for Marvel films. Devin over at Badass Digest has even more details about how closely 'Captain America 3' will tie into the upcoming 'Avengers' movies, including the scoop that 'The Winter Soldier' directors Joe and Anthony Russo are in talks to direct both the third and fourth 'Avengers' films.

For those unfamiliar with the Civil War story, it's a major deal in the Marvel universe, as it sees Tony Stark and Steve Rogers set at odds over the Superhero Registration Act, which requires those with superhuman abilities to reveal themselves to the U.S. government and render their services as part of a police force. Stark is a vocal supporter of the SRA, while the patriotic Rogers is surprisingly against it, rallying others who agree with him to go on the run in order to avoid being imprisoned. This story divides heroes who were previously allied, and these huge changes begin with the devastation created by the events in 'Age of Ultron.'

Another thing to note is that Spider-Man is a huge part of the Civil War storyline, and if those rumors we've been hearing are true over at Sony, this could allow for Spider-Man to be incorporated into the Marvel Cinematic Universe pretty soon.

Chris Evans will also reprise his role for 'Captain America 3' and appears alongside Downey Jr. in the upcoming 'Avengers: Age of Ultron.' Both actors are expected to also appear in the third 'Avengers' film as well. Should things go according to plan, bringing the Civil War story to the big screen would pave the way for a fourth 'Avengers' film, with Tony Stark becoming a much less sympathetic character.

More From ScreenCrush