How Iron Man could die in Avengers 4
Iron Man dies in as a sacrifice to save the others, mirroring his sacrifice in the first Avengers film
In the first Avengers movie, Tony Stark flies the nuclear missile into the wormhole to save Manhattan and millions of lives. This is a big moment for his character, and for other characters seeing that Tony is a true hero. Though, of course he survives, he was prepared to sacrifice himself. We have seen set photos of the team presumably back in time at the Battle of New York, and it would make narrative and poetic sense if Tony does end up dying to save the world in Avengers 4. He has always been the most worried about the end of the world, and it would be a fitting, if horribly sad, end for his character arc.
Iron Man dies to save Peter Parker, or his death at least impacts Spider-Man strongly in Far From Home
Happy Hogan seems to have been on the set filming for Spider-Man: Far From Home. Also, given Peter’s new, black suits, it does seem like he could possibly be mourning Tony. If multiple other characters who are close to Tony end up in the film, this could be the sign that Tony is truly dead. It would be an interesting character arc for Peter if he has to deal with the death of Mr. Stark while also coming into his own as a hero. It would also make sense if Iron Man dies to save Peter Parker from the Soul Stone or wherever he is.
Iron Man goes back in time and dies there in order to change the future
As mentioned earlier, there have been set photos leaked of Iron Man, Captain America, and Ant-Man at the Battle of New York. Many have assumed that this means they go back in time to change the events of the future. Maybe, while at this battle, Tony Stark sacrifices himself and actually dies this time where he didn’t in Avengers. This could lead to many emotional moments between Steve and Tony and also be a way for the rest of the heroes to survive.