Just days after Robert Downey Jr. hinted his run of solo Iron Man films might be coming to an end, Captain America: Civil War directors Joe and Anthony Russo suggested Tony Stark should go a long hiatus if the actor decides to hang up his weaponized suit.

“It’s almost impossible to replace Robert, he’s the biggest movie star in the world,” Joe Russo told Forbes. “I think if and when he is done with the character I think you will find that Iron Man might disappear for a while. I think the only way that you could reboot that character is to give a generational gap that would allow another actor to at least have a chance to redefine that character without the enormous specter of Robert hanging over it.”

Russo added that there’s no shortage of superheroes to carry the torch going forward. ”There are so many characters in the Marvel universe that can pick up the ball and run without it through the next phase or two before you need to see Iron Man again, frankly,” Russo said.

In a March 8 interview with USA Today, when about the prospects for a a fourth installment in the Iron Man series, the Oscar-nominated actor said, “I don’t think that’s in the cards.”

The Iron Man series has generated nearly $2.5 billion in global box office since it began in 2008. Downey Jr. has also played Tony Stark/Iron Man in both Avengers films as well as the upcoming Captain America: Civil War.

David Eckstein is a writer living in Los Angeles.