In reality, no one wants to see their favorite superhero die. I know that I don't want to watch as Captain America falls to his knees, never to rise again. Just the thought of it makes my eyes watery. In Avengers: Age of Ultron, Scarlet Witch gave Tony Stark a vision that made my heart break.
There were all my heroes, slowly dying from something on an unknown planet. This is something no one goes into a movie hoping to see. Yet, at the same time, I want this to happen.
I don't want a James Bond moment.
With an intricately woven universe, you fall in love with the characters. It takes strong and amazing characters to keep up excitement. This means the writers and actors have to work hard to prevent these characters from becoming old news. Usually, they do their job so well, you also get attached to the actors who play the characters. However, time goes on and actors get older. Or maybe, the hero does become old news and becomes stretched too thin.
So what happens? In James Bond, the actor just changes with no explanation. It has been rebooted many times. There have been six official James Bonds played by different actors. Since there was no distinction between the different spies, it was confusing. What would happen if we did this with the current Marvel Cinematic Universe?
What if they did this with someone like Iron Man?
Who in the world could pull off Tony Stark better than Robert Downey Jr? What if we walked into the theater to see Captain America: Civil War, and there was this strange looking man in the Iron Man suit? We would protest! You can't even place someone who just looks like Downey in the suit. There would be painful agony all around.
These characters can't just be easily replaced like Colonel Rhodes was between Iron Man and Iron Man 2. Rhodes was a secondary character, and it barely worked. It would be extremely noticeable if they did this to one of our favorite heroes, or even if they did it to Rhodes now that he became more of a major character. Someone like this can't be in a state of continuity like the Bond character is. This is why our favorite heroes will have to die at some point.
So we have no choice?
I don't think that we necessarily never have to see these characters ever again. What could be done is someone younger coming up to take the mantle.
Remember this kid from Iron Man 3? This is the boy that Tony Stark met in Tennessee. He helped Tony bring the suit back into operation. At the end of the movie, we see that Harley gets a 'little' present from Stark to thank him for his help. I don't know if we will see him again, but his presence gives us a small hope in the future of our favorite heroes.
Someone like this is how we could have another person come in and take up Iron Man's place. He couldn't be Tony Stark, but he could still be Iron Man. In the comics, Colonel Rhodes takes Iron Man's place. He does this to save the face of Iron Man after Stark retires and has an alcohol problem. With Rhodes now in the Avengers, it has become a possibility that we could very well see in the future! It's another way that is still not replacing Tony, but still getting to keep Iron Man.
It would also work to use someone like Rhodes to replace Stark because he is already his own character. If a whole new person came in to replace Tony, we would have the risk of this new guy pretending to be Robert Downey Jr. This would be as painful as someone just showing up with no explanation.
So, either way, I still wholly believe our favorite heroes have to die. I don't want someone to come in pretending to be Tony Stark. We wouldn't like him. Whoever he would be, he wouldn't be Stark. It hurts to think about it, and I'm already preparing myself for the worst in Captain America: Civil War, but I do think that this is the best way for our heroes to come to an end.