Could we have seen a much younger Thanos in the MCU movies? It turns out that yes, we almost did, as the concept sketches were just released. It looks like there were plans to introduce an origin story for the Mad Titan in either 'Infinity War' or 'Endgame,' but plans were scrapped. While it does appear that Thanos has been destroyed for good, there is a chance we might get to see more of his backstory in future MCU movies.
What Happened To Those Scenes?
It turns out some scenes from Thanos's youth were planned by writers Christopher Markus and Stephen McFeely. They originally were going to show the young Thanos in 'Infinity War' trying to save his home planet from overpopulation. However, those scenes ended up being discarded. Markus explained in an interview exactly how they came to that decision.
“We wrote some scenes, sort of flashbacky scenes of a young Thanos on Titan trying to make his case,” said Markus. "And part of the reason it went away is it got a little too Jor-El on Krypton making his case, you know?”
What We Got Instead
Instead of the young Thanos scenes, we got the flashback scenes to Thanos and the young Gamora. After wiping out half of her planet's population in order to 'save it,' Thanos ends up taking little Gamora with him and declaring her as his adopted daughter.
“And it’s a scene that’s only doing one thing. What we settled on were all those scenes that explained any history he had with Gamora,” Stephen McFeely said.
“Those [scenes] are doing more than one thing because they’re highlighting his relationship with the daughter he’s going to have to sacrifice.”
We Get to See What Young Thanos Looked Like
We didn't get to see the young Thanos, but we did get to see the concept art that was planned out. Ryan Lang, who has worked on many Disney and Pixar films, just recently released the sketches and art he worked on the depict what the young Thanos looked like and even sketched Thanos's family portrait.
We see that Thanos doesn't look a great deal differently than he did in his roughly middle-aged form as played by Josh Brolin, except that he's much slimmer and more youthful.
There's Still A Chance We Might See See Young Thanos
Although we didn't get to see him on-screen this time, there's still a good chance we might get to see the young Thanos in the future. Marvel is coming out with 'The Eternals' next year, and even though Thanos is supposed to be dead, we might still see his young self in some flashbacks. Since Thanos was technically an Eternal, next year's film would probably be the place to show more of Thanos's backstory. That's not a guarantee, but it certainly would make a lot of sense in the MCU.