Now it is no secret that RDJ is getting older. He might still be awesome but less face it soon after Infinity Wars our metal made hero will soon retire. But don't worry guys Marvel has done its best to provide a storyline on why he hangs up the suit, and they have been building it up with every movie he's been a part of.
Let's start with The Avengers: Age Of Ultron. Ready? Come on stay frosty.
Avengers Age of Ultron
Tony Stark got a lot of heat from this movie since he was the one who created or rather resurrected Ultron from the sceptre. He also did it without consulting any of the other Avengers except for Banner. Ultron was created because of him, and all the carnage and death that followed Tony took upon his soldiers.
So all of the carnage and pain that followed Tony took upon himself. He also probably took the death of Quicksilver on himself since Ultron was his doing. He also was indirectly or directly (whichever view point you look at it from) involved in the death of the parents of the Maximoff Twins. That's why they originally sided with Ultron because they wanted revenge on Tony. Their death you can believe Tony took on his shoulder as well.
The transformation that Tony Stark has been too is overwhelming. From a fun loving, sarcastic,genius, billionaire, playboy, philanthropist iron suit wearing alien killing machine to a guy who now carries the weight of loss of life because of his actions.
This directly leads us into Captain America: Civil War.
Captain America: Civil War
It will be Captain America vs Stark. But this will be a different Tony. He will fight for all he has not because he is being made the villain in the movie but that is what he believes now. There will be a lot of carnage and I believe that there will definitely be a side that wins but nobody will come out of it unscathed.
So by the time the big bad Thanos comes to Earth Tony will have aged. I believe that Marvel executives could do one of two things. It's theory time guys! Are you ready? Alright then.
Tony Stark dies in the Infinity Wars at the hands of Thanos like he did in the comics. I believe this should happen at the end of the first movie since it would leave the audience and the heroes on the screen with a massive jolt of reality. It would also leave a little suspense as well as generate revenue for the next one since people would have to see what happens next.
Also it would give our heroes a chance to rally and defeat the mad Titan.
In this theory Tony hangs up his boots after Thanos. The wreckage is too much for him to bare. So he passed on the helmet to who some people including myself believe to be the kid from Iron Man 3.
So what do you think will Tony finally hang up his boots in Infinity Wars?