Avengers: Infinity War's conclusion is now infamous: the heroes lose. Half of them disappear. After the credits, the last thing we see is Nick Fury call for Carol Danvers before he literally turns to dust.
For all their might, the Avengers, the Guardians of the Galaxy, and their assorted allies could not stop Thanos from carrying out his ultimate plan. At one point, they tried literally pulling the Infinity Gauntlet from Thanos' hand before he collected the last gem. (No one thought to bring a hacksaw or a laser capable of burning off an all-powerful being's skin.) Hulk was no match, and he's implied to be the strongest there is. Thor in his god-like power nearly got there, but narrowly missed striking a fatal blow. Everyone else fell well short.
Given that there are years of Marvel movies ahead, it's safe to say some of those deaths won't be so permanent. It's unlikely, after all, that Marvel would let its new breakout hero Black Panther stay dead so soon after the phenomenal success of his solo movie. A Spider-Man: Homecoming sequel is expected to premiere in theaters on July 5, 2019, and Guardians director James Gunn has announced that his script for Vol. 3 is well on its way.
But given who's left over at the end of Infinity War, how can the MCU possibly turn back the clock and undo a majority of the damage done by Thanos without simply giving him a two-hour lecture on the pitfalls of Malthusianism? No one on Earth can stop Thanos — is bringing Hawkeye and Ant-Man back to the fold in the as-yet-untitled Avengers 4 really going to help?
No. And that's why Captain Marvel is going to be a critical point for the Marvel Cinematic Universe going forward. Because, and this is all my own conjecture, Captain Marvel (2019) is going to introduce forces beyond Earth that will reverberate through the MCU.
We already know Captain Marvel, starring Brie Larson as Carol Danvers, aka Captain Marvel, will take place in the past. There will probably be a Discman joke. But there will also be the introduction of the Kree, a fairly mighty alien race, and the shape-changing Skrulls, a fairly duplicitous one. While Captain Marvel herself is human, most of the other characters in the film are expected to be either Kree or Skrull. And while we've seen cosmic action throughout the two Guardians of the Galaxy films, we've seen the sort of scumbag end of the greater universe, the lowest rungs on the cosmic ladder, the scavengers and n'er do-wells — the a-holes.
Basically, to beat Thanos, we'll need otherworldly strength. And that's why, in my mind, it's going to be the true introduction of the cosmic-level Marvel heroes the MCU has been shying away from thus far.
It makes sense for Disney. Introducing cosmic-level Marvel heroes is a way to bring in new science fiction adventures a la Star Wars based on intellectual property the company already owns. Bringing in these heroes opens up doors for movies radically different from another Captain America romp, and it makes sense in the context of the MCU, as doing so would make it a true universe in ways both Guardians of the Galaxy movies and Thor: Ragnarok have only hinted at thus far.
So imagine, if you will: Thanos wipes out half the universe. Most of the remaining Avengers and fighters are the heroes who don't have innate powers and rely on technology or toughness to win battles — Captain America, Iron Man, Black Widow, War Machine, Okoye, and maybe Ant-Man and Hawkeye — as well as a suped-up Thor and a semi-depowered Hulk. Rocket Raccoon is still kicking, too, but certainly isn't a powerhouse on the order of Captain Marvel. This scrappy group will need help.
That help will likely come from Captain Marvel.
It's safe to say Mar-Vell (the original Captain Marvel who was instrumental in the transformation of Carol Danvers into Ms. Marvel in the comics, who then became the new Captain Marvel) won't survive Captain Marvel, but other Krees might. And hey, maybe they're going to introduce Monica Rambeau along the way in the movie.
Guardians of the Galaxy also introduced the Nova Corps, who would be able to lend a hand — possibly paving the way for Richard Rider or another Nova to make it on-screen. Guardians also hinted at Warlock's cocoon, meaning Adam Warlock could naturally pair with the Infinity War follow-up. That, too, could bring us the Infinity Watch members Moondragon, Maxam, and Pip the Troll (Gamora and Drax, Infinity Watch members in the comics, perished in Infinity War). And Marvel is reportedly itching to make an Eternals movie, which would give us Sersi and Starfox, both of whom are from the same species as Thanos and may have a bone to pick with his indiscriminate mass killing. Maybe even Inhumans TV show was an abortive attempt at inching towards a cosmic-level MCU and could be partially incorporated into the MCU proper.
There are other characters Marvel could pick up on and amplify in profile, like Quasar, Firelord, Darkhawk, or other C-list (for now) cosmic heroes. Remember that the Guardians of the Galaxy weren't exactly Captain America-level famous comic book characters before Gunn and the MCU bosses brought them to the big screen, backed by the likes of Zoë Saldana, Bradley Cooper, Vin Diesel, Dave Bautista, and star-in-the-making Chris Pratt.
Oh, and let's not forget Beta Ray Bill! With an MCU suddenly gone cosmic, it's a great entry point for one of the most beloved Thor characters to clop right in. It could also lay the foundation for a later incorporation of Galactus and the Silver Surfer into the MCU should the merger with Fox go through (and Comcast doesn't derail it).
All of these characters could bring in a firepower greater than Earth's mightiest have ever been able to muster. It could explain why the next Avengers movie is still untitled, and why there are few inklings as to what comes next in the MCU aside from a few threads.
Captain Marvel may be the key to unlocking the MCU going forward. And in ways only hinted at before, the future may be in the stars.