No one is ever truly gone. As multiple sites are reporting, it looks like Robert Downey Jr. will be stepping into the boots of Iron Man one last time for the upcoming Black Widow film. A prequel title in the MCU, it seems RDJ just couldn’t let go of the character after Endgame gave him the perfect out. As for how this will work, it seems Black Widow actually takes place after Captain America: Civil War, which means Tony and Natasha will have already been acquainted by that point.
There’s a precedent for having Tony appear in the Black Widow film. Scarlett Johanssen’s character was actually introduced into the MCU in Iron Man 2, so the two go back quite a bit. Natasha also teamed up with Tony in Civil War, so it makes sense the two would stay in contact after that film. I could see RDJ’s role amounting to him berating Natasha a bit, then wishing her well on her next journey.
I’m just not sure how I feel about this happening so soon after Endgame. Spider-Man: Far From Home did a great job handling the fallout of Iron Man being gone, but then the very next film in the MCU is going to have him back. I know this is a prequel and all, but I feel a better way to handle this would be to release Black Widow after a few more entries and to keep RDJ’s involvement secret. Whatever the case, it looks like we haven’t seen the last of Tony Stark.