Time right for Marvel to introduce planet-eating Galactus as the next big baddie in phase 4
In Thanos, the Infinity saga introduced the first formidable villain that the MCU had ever seen. The mad Titan killed with ease and matched up to each of the Avengers. Since his introduction in the 'Avengers', every movie from then on played a role in explaining who he was and his plan to restore balance to the universe.
The Deviant was finally snapped out of existence by Tony Stark, aka Iron Man (Robert Downey Jr.), and with phase 4 looming, the focus has moved to who the MCU's new big bad would be.
By the looks of it, it may seem to be Galactus. For now. There have been theories about how Thanos' second snap at the start of 'Avengers: Endgame' was more of a beacon for Galactus to make his presence felt.
Galactus was formerly human. He goes on to become a cosmic entity who consumes planets to sustain his life force. He first appeared in the comic book Fantastic Four #48, published in March 1966.
It also makes sense to introduce Galactus at this point as it appears Marvel's focus in phase 4 is predominantly on cosmic superheroes. With 'Guardians of the Galaxy' set to release the third volume sometime in 2022, it seems apt to bring in the mega villain who can throw down the gauntlet to the superheroes.
After all, there was an easter egg that Galactus was shown in 'Guardians of the Galaxy' when the Collector rolls out the origin story of the MCU's Infinity Stones, complete with projected video to illustrate their power. The stone discussed is the Power stone.
It is still unclear if 'Thor: Love and Thunder' and 'Doctor Strange in the Multiverse of Madness' may hint Galactus coming in. Plus, there is a 'Captain Marvel' sequel in the works and 'Eternals', both of whom are related to the Purple Planet Eater.
The other villain who may probably get to terrorize the universe is Annihilus. He is, after all, the baddie supreme and has had run-ins with Thor and the Guardians. Fueling this theory is a Nova movie that's already in development.
Considering this is true, and if we are to go by the narrative in the comic series 'Annihilation', the movie is most likely to be an origin story about Richard Rider, a member of the intergalactic police force, Nova Corps, with superhuman abilities including enhanced strength, flight, and resistance to injury.
Then, ideally, the plot would revolve around Annihilus, the intergalactic supervillain who leads an armada of warships, setting off an annihilation wave that destroys planets. While some cosmic heroes such as Star-Lord and Drax (both are Guardians of the Galaxy at the moment) try and fend off the attack, they find an able ally in Nova, who stops the wave and ultimately kills Annihulus in the process.
Ever since the writers of 'Avengers: Endgame' revealed that they had plans to introduce Nova briefly in 'Infinity War', there have been many theories about how the 'Human Rocket' would be introduced in the MCU. However, Nova is a notable absentee in phase 4 and that means Annihilus may have to await his turn.
Our money is on Galactus.