Tony Stark was the main man in the Marvel Cinematic Universe, and the conduit through which all of the major plot beats flowed, so it wasn’t surprising that the franchise’s resident genius billionaire playboy philanthropist was the person to crack the formula for time travel and set the plot of Avengers: Endgame into motion.
Obviously, the idea came from Scott Lang, but his suggestions were swiftly shot down as being unhelpful. If anything, Peter Parker was the driving force behind Tony’s decision to come back in from the cold, with the loss of his young protege continuing to haunt him five years later.
Introducing time travel in any movie presents all sorts of narrative and logical problems, of course, but it all worked out in the end. However, it seems that Stark may have teased the impending arrival of Kang the Conqueror at one point as well, and very few people caught it.
Jonathan Majors has been cast in Ant-Man 3 and while it hasn’t been officially confirmed yet, he’s widely believed to be playing the aforementioned antagonist. If you’ll recall, in Avengers: Endgame, Tony told Steve Rogers that when you mess with time it tends to mess back, and with the conclusion to the Infinity Saga featuring several timelines and the future of the MCU hinging on the multiverse, that certainly could have been a hint at things to come.
As ScreenRant explains:
At one point in Endgame, a baffled Captain America asked Iron Man what happened, to which Tony replies: “you mess with time, it tends to mess back.” Granted that at this point, the commotion was due to the Mad Titan coming for the Avengers from a different timeline, this proves that Iron Man was aware that their time-hopping activities will have repercussions which may very well include the arrival of Kang who’s villainy is defined by time travel.
In the comic books, Kang is born in the 30th Century and uses time travel to conquer various worlds throughout history. Now that time travel is canon in the MCU, the intergalactic villain could set his sights on modern day Earth as the next target of his quest for total domination, with the planet’s vast roster of superheroes posing just the sort of formidable but not impossible challenge that he enjoys when enslaving a new world.