Mark Ruffalo headlined a recent panel, Mean and Green: Mark Ruffalo Spotlight, at the just concluded Emerald City Comic-Con in Seattle, Washington. During the panel, the actor, who currently stars as Bruce Banner cum the Hulk in the Marvel Cinematic Universe, was asked whether Robert Downey Jr. will return in some form in the nearest future. The actor wouldn't give a definitive answer but he did provide a coy response.
He stated that the death of Downey Jr.'s character, Iron Man, in Avengers: Endgame was a sad occurrence, before adding that there is a time machine in the MCU, suggesting that Marvel could bring the character back. He pointed to the fact that the franchise now has alternate universes and realities to buttress his point.
When he was pressed to clarify his response, he jokingly looked up at the hall ceiling before responding, "Are one of these boards going to fall on me? Man, are you trying to get me in trouble again? I'm not going to say it's not possible, but I'm not going to say it is."