Robert Downey Jr., the MVP of the Marvel movie universe and highest-earning actor in Hollywood, is open to “Iron Man 4,” because, well, why not?

“It’s that thing of: Why give up the belt when it feels like you can barely get jabbed?” Downey said when Entertainment Weekly popped the big question on the set of “Avengers: Age of Ultron.”

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After tense salary negotiations in 2013, Marvel announced Downey would return as Tony Stark for two “Avengers” sequels, but did not mention a deal for another “Iron Man” movie.

While Downey suggested he’s not ready to retire as Marvel’s man in the iron mask any time soon, he did firmly place the ball in the studio’s court. And since “Iron Man 3” grossed $1.2 billion in theaters around the world last year, it’s hard to imagine his employers don’t want to play.

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“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,” Downey said. “When things are going great, there’s a lot of agreement.”

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Fans shouldn’t get their hopes up, though, because as Downey puts it, “The future, as usual, is uncertain.”