He's most likely stating the obvious here, but in an interview with Nightline on ABC News, Iron Man himself, Robert Downey Jr. admitted he'd be up for doing Iron Man 4. The interview took place during a piece on Captain America: Civil War and ABC's Nick Watt managed to get it out of him (though I imagine it wasn't that hard).
"I feel like I could do one more" said Robert Downey Jr.
Check out the full piece below. The chatter about the possibilities for Iron Man 4 begin at 3:55.
We haven't seen an official Iron Man movie for almost three years now since 2013, though the character has been kept relevant through The Avengers films and cameos through various Marvel movies. Iron Man is confirmed to appear in the upcoming Spider-Man: Homecoming movie, so it's already clear that Robert Downey Jr. has no plans of letting his take on Tony Stark go any time soon.
Source: [ABC News]
