The actor's dwindling Hollywood career got a kick after he appeared in 2008 film 'Iron Man', and he's since gone on to reprise the character twice more in "Iron Man 2" and "The Avengers".
A third "Iron Man" movie is in the works, and Downey, Jr. is keen to keep playing the character providing the films retain the same high quality, reports express.co.uk.
"I would really hate for someone else to think they could step into my shoes. I know things are looking like that they (sic) could go on for a long while," the actor told MTV.
"As usual in my book, it's all about quality control and delivering a product that you can have this kind of reaction to. If they keep doing that, maybe I'll keep showing up," he added.