Tony Stark/Iron Man (Robert Downey Jr.) met his end in Iron Man. While there's no official word about Downey reprising his role, there are several ways that Marvel Studios can bring him back.
After the heroes' devastating loss in Iron Man sacrificed himself for the greater good - wrapping up his decade-long arc in a poetic way.
Just because Iron Man is dead in the present MCU, that doesn't mean that Marvel Studios can't bring him back in one of their projects, some of which are prequels or partially take place years before Iron Man's death. Here are all the Phase 4 films and TV shows that Iron Man can appear in.
Black Widow
Kicking off MCU's Phase 4 is Cate Shortland and Scarlett Johansson's Iron Man 2 which also marked Black Widow's debut outing.
In conjunction to this, there have been persistent rumors that Downey will make a cameo in the film. However, when asked about it, he remained tight-lipped. In any case, between Black Widow's time setting and what appears to be its narrative, seeing Iron Man factor into the movie's story is not outside the realm of possibility.
Shang-Chi and the Legend of the Ten Rings
It doesn't seem like Ant-Man proving that they're still very much around.
Shang-Chi is set to further explore the Ten Rings with the imminent introduction of the real Mandarin played legendary Chinese actor Iron Man 3 teased of the eventual reveal of the mysterious warlord, but it turned out to be a red herring. Regardless, now that he's officially coming to the MCU, fans might learn more about him and his organization's secret operation in the universe, including revisiting their involvement in the Iron Man trilogy.
Doctor Strange in the Multiverse of Madness
Doctor Strange (Benedict Cumberbatch) and Iron Man have a lot in common - both are sarcastic geniuses who were led down unusual paths to become superheroes. The pair didn't meet until the events of Infinity War where they prepared to battle Thanos. They worked closely throughout the movie until Strange was turned to dust via the Decimation. Prior to his disappearance, though, Strange discovered what needed to happen in order for them to win in Endgame, which included Iron Man's death. While they didn't get to share the screen as much in Endgame, there's still a chance for them to come together in Doctor Strange in the Multiverse of Madness. As the title suggests, the movie will see the sorcerer explore more of the multiverse which Marvel Studios has been teasing for a while now.
Their potential encounter in the sequel movie has one big caveat, though. Since it's the multiverse, Strange could encounter a different version of Tony Stark living in another reality. Depending on the alternate universe, this iteration of the character may not even be remotely similar to the one fans loved in the primary MCU timeline. In any case, it would still be an interesting scenario to see in Doctor Strange in the Multiverse of Madness, especially if it means seeing Downey approach the role a bit differently.
Spider-Man 3
Iron Man was instrumental in bringing Spider-Man into the bigger MCU. Through his mentorship, Peter Parker was able to slowly become the hero fans know him as now. Tony was a factor in both Spider-Man 3 are still tightly under wraps, fans can expect that somehow Iron Man will factor in its story. Perhaps not as integral as the previous movies, but it would be odd for the threequel to not even mention the character.
Tony's possible appearance in Spider-Man 3 can happen in a few ways, but the easiest one is through a personally-recorded message accessed through E.D.I.T.H.. Getting some words of encouragement from his mentor as he deals with the aftermath of his battle with Mysterio would be a great boost for Peter. One of the common criticisms of MCU's Spider-Man franchise is that the movies are a bit too reliant on Iron Man. An appearance through a video recording allow Marvel Studios to capitalize on Tony and Peter's bond and use it for emotional impact without undermining the sequel's story.
WandaVision
Marvel Studios is broadening the MCU's horizon by producing TV shows exclusively for Disney+, which includes connect to Doctor Strange and the Multiverse of Madness, with Olsen reprising her role in the movie as well. Considering the direction WandaVision appears to be going in, an appearance from Iron Man may seem unlikely, but since he created both JARVIS and Vision, he might be instrumental in explaining how he returns from the dead. If Marvel Studios doesn't want to bring Downey in for a short stint on TV due to budgetary concerns, they can repurpose unused footage of him that can work within the premise of WandaVision.