The Winter Soldier himself, Sebastian Stan, has confirmed his involvement with the untitled Avengers 4 blockbuster. In an interview with CinemaBlend, the actor said,
“I still haven’t read a script for this next one. For this fourth one. All I know is I’m going down there in October, and that’s all I know. I still actually haven’t read a script for the last one. [laughs] All I knew was what I was involved in, and I was kept on a very ‘need to know’ basis. Maybe that’s the norm. But it’s a family system. There’s a trust, and there’s a sense of knowledge between the writers and the directors, with Kevin [Feige]… that shows up.”
Details about the fourth Avengers flick are very scarce. By the sounds of it, even the actors involved in the film have no idea what is going on. Stan did touch on that, saying he was totally confident in Marvel and the direction they would take with all the characters.
The Russo Brothers are returning to helm the film, which is set to release on May 3, 2019. Avengers: Infinity War will hit the big screen on May 4, 2018.
Source: Heroic Hollywood