The next Captain America film, which is officially set for May 6th 2016, will use elements of Marvel's mega-crossover Civil War. The highly-controversial storyline saw the superhero universe fractured over the Superhero Registration Act, which forces everyone with powers to become registered with the government and reveal their civilian identities to the public. One team of heroes, led by Captain America, fought against this idea. Tony Stark led the other faction that believed in the registration act. That led to a massive "civil war" that split up the Avengers and caused the entire hero community to distrust one another. It also was a key step that led to Captain America's eventual "death".
This is a pretty big deal for a few reasons, but primarily it keeps Downey under the Marvel umbrella for awhile longer. He wasn't signed on for any appearances after The Avengers 3, and apparently negotiations were tense with Marvel nearly ending them altogether. But there's even more, as Variety's piece states “The fallout from the government and Stark’s actions would factor into a new 'Avengers 4' film and beyond that will assemble new characters being introduced like Ant-Man and Doctor Strange, among others, in their own movies.” This seems to fit with recent rumors of a major lineup change for Avengers 3 that would see most of the original cast left out.
Finally, this means Captain America 3 will be a bigger part of the Marvel cinematic universe as a whole rather than a standalone film. To that effect, Badass Digest says Captain America: The Winter Soldier and Captain America 3 directors the Russo Brothers are in talks to helm Avengers 3 & 4.
So this is a lot to take in but the point is that Marvel is flipping the script once again and taking the superhero genre to a different level.
