If you can be sure of one thing, it’s that Marvel will keep putting out Iron Man films until we stop paying to see them. You can also be sure that Robert Downey Jr. will be demanding lucrative pay structure to return to the franchise.

Iron Man 3Robert Downey Jr. shooting Iron Man 3

The actor, who played Tony Stark and his iron-clad alter-ego for the first three films to both critical acclaim and fiscal success, was named as the highest earning actor working in Hollywood by Forbes for the second year running, and a huge part of that was down to his work on Iron Man 3, which grossed $1.2b from the global box office.

In a new interview with Entertainment Weekly, Downey confirmed that a fourth Iron Man film, with him starring, isn’t beyond the bounds of possibility. "It's down to Kevin Feige and Ike Perlmutter and Disney to come to us with what the proposal is, and that's on us to agree or disagree,” he said. But if he's too expensive, then there's always the Colin Farrell option - he wasn't anywhere near the Forbes earners list, and would represent a cheaper option. 

More: Surprise, Surprise: Thanks To Marvel, Robert Downey Jr. Continues His Reign As Hollywood's Richest Actor

Although money might not be the stumbling block. It’s likely that Marvel would pay a huge amount to have Downey Jr. back, should the plot allow it to happen, but with rumours abounding that Stark is killed off in the upcoming Avengers sequel, Age of Ultron, his presence in the new movie is under scrutiny. Downey Jr. himself seems sure he’ll be back. “It’s that thing of: why give up the belt when it feels like you can barely get jabbed? Most people are saying that right when they get knocked out,” he said, adding: “The future is, as usual, uncertain.”

Either way, Iron Man 4 will go ahead. "I believe there will be a fourth Iron Man film and a fifth and a sixth and a 10th and a 20th," Marvel Studios president Kevin Fiege said last year. "I see no reason why Tony Stark can't be as evergreen as James Bond. Or Batman for that matter. Or Spider-Man. I think Iron Man is a character just like that."