Avengers 4: Every Character Confirmed So Far
19. Bucky Barnes
Confirmed By: Sebastian Stan
Despite the fact that Bucky was the first victim of Thanos' snap to disappear, Sebastian Stan has announced - in an interview with CinemaBlend - that he's returning for the sequel, though he hasn't actually read the whole script on account of Marvel's security measures.
Presumably, at some point he's going to come face to face with Tony Stark again, which could be very interesting.
He also confirmed there's at least one scene where EVERYONE shares the screen together like a huge comic book splash page. So that's exciting.