For now, Marvel is believed to only be shooting scenes for Doomsday, with the timing of Reynolds' post strongly suggesting he's set to return for that, rather than later down the line. Indeed, some fans are eagerly anticipating a second big reveal of Avengers: Doomsday cast members, perhaps via a second set of chairs, as production continues.

A cryptic new Instagram post from Ryan Reynolds has fans speculating that the actor could be returning as Deadpool in "Avengers: Doomsday."

Doomsday, and it's exactly what the movie needs. The story of Avengers: Doomsday is mostly unknown at this point, aside from the involvement of Robert Downey Jr. as Doctor Doom, the film's main villain.