The movie that put an end to the Infinity Saga, Avengers: Endgame, was a grand success in cinema - with great feedback from both viewers and critics, as well as strong performance in the box office. As a whole, the movie has brought in nearly 2.8 billion dollars globally. It's hard to think that the MCU's empire was started it all from 2008's Iron Man - which, back in that day, was thought to be a B-rated superhero in Marvel's comics.
And a recent interview with Endgame's writers Christopher Markus and Stephen McFeely has revealed the path to success of the MCU, that is avoiding making many possible mistakes that might occur when maintaining a long-running franchise - for example, avoid making films like Iron Man 4 if it doesn't fit in the big picture of storytelling.
As we all know, at the end of Avengers: Endgame, to push away Thanos and his legion - Iron Man has ultimately snapped his finger while wearing the infinity gauntlet with all the stones embed - resulting in the loss of his life. According to the writers, planning for Infinity Wars and Endgame was started back when they're still making Captain America: Civil War, and for this reason that Tony Stark was being a major character in this movie. And also, the writer believed that "if it's another studio, then you probably had an Iron Man 4 movie."
The death of Tony Stark is a necessary thing, and it makes the entire Infinity Saga of the MCU "start with Iron Man, and end with Iron Man". While keeping Tony Stark alive for more and more movies might be profitable - as many people love Tony Stark now - it would have hurt the entire MCU in the long run.
"We realized at one point, late in 2015, that for Steve to be his best self, he was going to have to get a life, and for Tony to be his best self, he might have to lose his." - The writer shared.