It was only three years ago that Robert Downey Jr. ignited speculation he might never suit up as Iron Man again. However, that was before he negotiated a new contract with Marvel Studios that led to his roles in "Avengers: Age of Ultron" and "Captain America: Civil War."

Since then, the highest-paid actor in Hollywood has signed on for "Spider-Man: Homecoming," and is expected to appear in the two-part "Avengers: Infinity War." However, if you thought you'd seen the last of Downey in an "Iron Man" movie, you may want to think again

In a segment on "Civil War" that aired on ABC's "Nightline," the actor says, "I feel like I could do one more."

Of course, there's no "Iron Man 4" in Marvel's immediate future, but considering the amount of money brought in by the third film alone ($1.2 billion), it probably wouldn't take much convincing for the studio to change those plans.