At the end of Avengers: Infinity War, Thanos has just snapped half the universe out of existence, and the Avengers and their allies weren't in such great shape. While the original six (Iron Man, Thor, Captain America, Hulk, Hawkeye, and Black Widow) are still around in Endgame, out April 26, they've lost a good number of the world's greatest superheroes. But what happened in Infinity War didn't come out of nowhere. Back in Age of Ultron, Iron Man had a vision about destruction, and not all of it has come to pass yet.
The chaos and devastation that befell the MCU in Infinity War may have been foreshadowed way back in the second Avengers film. In Age of Ultron, Scarlet Witch — who possesses mind-altering powers — gives all the Avengers visions of their worst fears and greatest longings, which ultimately contributes to their division in Captain America: Civil War. Iron Man's vision involved a defeat, his teammates helplessly on the ground dying. Captain America was scolding him for not having done enough to prevent this, and the alien armies of the Chitauri were approaching Earth once more as they did in The Avengers.
Now, because Scarlet Witch projected this vision in Iron Man's mind while they weren't playing on the same side, and because her power is to alter minds, the vision isn't necessarily a truthful indication of the actual future. Still, many fans tried to connect those dots before Infinity War came out last year. However, the Avengers who die in his vision are the ones who survived the Snap. So it's possible that what Tony saw could still come to pass in Endgame.
If anything, the vision's haunting effect on Iron Man will only be stronger in this last movie than ever before, since it's their last chance to defeat Thanos and save the universe. And because it seems that the hero would do anything to ensure that his vision won't come true, there's speculation that he might perform an act of self-sacrifice in Endgame. After all, he's knowingly risked his own life for the good of the world before, having even died very briefly with his deactivated Arc Reactor in The Avengers.
The theory of Tony Stark's death is very plausible given that Endgame is also said to be Robert Downey Jr.'s last film before he finally hangs up his metal suit. Downey Jr.'s co-star Chris Evans told Good Morning America in an interview last year, "A lot of our contracts are through. Myself, Downey Jr., [Chris] Hemsworth, we all started roughly at the same time, and I think we all through Avengers 4 kind of wrap it up. I don't know what's next — but by 2019, that's it."
Given the vision, Stark's current state of mind, and his willingness to go great lengths to ensure the safety of his friends and the universe, Endgame seems to be a reasonable exit for the hero. Though Tony Stark's death wouldn't necessarily mean the end of Iron Man, let's hope neither these predictions — nor Stark's vision — actually come true.