Everyone has been asking Robert Downey Jr. to return to the Marvel Cinematic Universe. And now he is … but not as Iron Man. At their big San Diego Comic-Con panel, Marvel Studios confirmed that the next film in the Avengers franchise is Avengers: Doomsday — the Avengers (and the Fantastic Four, apparently) versus Doctor Doom. And playing Doctor Doom in the film is … none other than Robert Downey Jr. You can see (and hear) the reaction to Downey’s reveal below. READ MORE: Every Big Marvel Cameo in Deadpool & Wolverine Downey is not the only person returning for Avengers 5 either. Marvel confirm…