On the surface, Avengers: Endgame introduced the complex idea of time travel to the Marvel Cinematic Universe — but if you start digging deeper, a whole new can of worms could have been opened up. As evidenced by Scott Lang's (Paul Rudd) brief time-traveling woes, the Quantum Realm technology has the ability to make the characters of the MCU immortal — in a sense.
As u/ak2sup points out in a now-viral post, Lang was turned into both a pre-teen and old man and seemingly carried his thoughts and memories across the transformations. That means with the Quantum Realm tech already developed, the Avengers could theoretically revert Captain America (Chris Evans) back to his age before he traveled back in time. The technology would act similarly to the Time Stone, allowing just one person or item to be impacted while the rest of the timeline remains the same.
It should be noted that Tony Stark (Robert Downey Jr.) mentioned at one point the situation was dangerous — but with everything else they've figured out, there's got to be someone that can stabilize the tech. Another large question would be the moral obligations with using technology like that. Could people just line up and keep reverting themselves to a young age to prevent dying? What happens if someone managed to fall ill — would they be able to go back in time prior to their sickness and all would suddenly be well?
Then on top of everything else, if the powers that be chose to pursue the time-traveling and immortality bit any further in Phase 4 and beyond, you could bet your but some bad guy would end up after the tech anyway.
Do you think someone will eventually use the Quantum Realm tech for immortality? If so, who? Share your thoughts in the comments below or by tweeting me at @AdamBarnhardt! Avengers: Endgame is now available digitally ahead of a home media release on August 13th.
Upcoming Marvel Studios projects include Black Widow on May 1, 2020, The Falcon and The Winter Soldier in fall 2020, The Eternals on November 6, 2020, Shang-Chi and the Legend of the Ten Rings on February 12, 2021, WandaVision in spring 2021, Loki in spring 2021, Doctor Strange in the Multiverse of Madness on May 7, 2021, What If? In summer 2021, Hawkeye in fall 2021, and Thor: Love and Thunder on November 5, 2021.