Robert Downey Jr has strongly hinted he may end his career-transforming stint as superhero Iron Man.

Speaking to GQ magazine, Downey Jr suggested the role, which made him an A-list superstar in his 40s, could become a bore if he were to continue too long, and noted that he was out of contract. He referenced an ankle injury suffered on the set of forthcoming sequel Iron Man 3 as a possible sign that he should consider a new career path.

"It got me thinking about how big the message from your cosmic sponsor needs to be before you pick it up," said Downey Jr. "How many genre movies can I do? How many follow-ups to a successful follow-up are actually fun?"

He added: "I come from a family of very innovative writers and directors and actors and artists, and the circle of friends they were in were the people I heard having pun-offs playing poker at two in the morning, and it was just the most comforting aspect of my childhood. So there's this kind of legacy of souls from what I consider to be a very particular time in entertainment, and I'm sensing a return to that."

Downey Jr is the son of cult film-maker Robert Downey and the late actor Elsie Downey, who appeared in many of her husband's films. Downey Jr has appeared as Iron Man/Tony Stark in four movies, including Iron Man 3, which is projected to be one of 2013's highest-grossing films. Last year's The Avengers, in which Iron Man united with Thor, Captain America and the Hulk to face down an alien invasion, stands as the third-highest-grossing film of all time with more than $1.5bn (£983m) taken worldwide.

Downey Jr also confirmed reports that he received a $50m payday for The Avengers thanks to a profit-share deal with studio Marvel and its parent company Disney. "Isn't that crazy? They're so pissed," he told GQ. "I can't believe it. I'm what's known as 'a strategic cost'."

Meanwhile, it has been reported that Iron Man 3 will be the first film to debut in the 4DX format in Japan, where it is being pioneered. The technology features tilting seats, blowing wind and artificial fog, as well as odour effects.