During their chat with Yahoo, the Russos went into further detail on what the plot might entail. Obviously, they didn't spill any spoilery specifics, but they did say that the third film will take place "a couple of years" after the events of The Winter Soldier and the now complex relationship between Steve Rogers and his friend Bucky Barnes (Sebastian Stan) will serve as the emotional core for the story they tell.
The filmmakers also hinted at some potentially big changes for the future of the franchise, teasing moviegoers with something new that will bring a "twist" to the material. What this means exactly is purely speculation at this point, but individuals with knowledge of the comics may have some idea where the Russos could be headed.
Chris Evans' contract with Marvel Studios is up after The Avengers 3, and the actor has gone on record saying that he's looking forward to move behind the camera and pursue a career as a director once that film wraps up. Unless Marvel is content with letting one of their most commercially viable series sit on the sidelines (unlikely), then some reshuffling will be in order if Captain America 4 is ever to become a reality.
Marvel Comics recently unveiled Sam Wilson, the Falcon (played by Anthony Mackie in the film), as the new Captain America. Given the company's habits of pushing certain developments to coincide with the films (see: the increasing presence of Rocket Raccoon prior to Guardians of the Galaxy), it's entirely plausible that Wilson's ascension from sidekick to captain will be a story beat covered in the MCU.
That said, the Russos specifically mentioned the Winter Soldier when describing their twist, meaning that a different part of the source material could make its way on the big screen in due time. Stan, as you may know, has a nine picture deal with Marvel and has only appeared in two, so he clearly has a lot more ground to cover before he packs it up. In the comics, Bucky took the mantle of Captain America following Rogers' death, and if the post-credit scene in The Winter Soldier is any indication, the groundwork is already being laid out for this to take place in the films as well.
While it's fun to theorize where the Marvel movies may go from here, it's important to keep in mind that we're a long way off from any of this actually taking place. Evans still has three films to do, and Avengers 3 won't be in theaters until 2018 at the earliest. As fans discuss what characters and projects the studio will develop through 2028, it seems as if the star-spangled man with a plan is all set for the time being.
Captain America 3 will be in theaters May 6, 2016.
Follow Chris on Twitter @ChrisAgar90.
Source: Marvel Studios, Yahoo Movies