We have finally reached the day where Doctor Strange in the Multiverse of Madness hits theaters! This movie is setting up to completely change the future of the MCU, as well as the past as we know it. In true Marvel fashion, they are always building toward something. Accordingly, I present my theory for how Doctor Strange in the Multiverse of Madness will set up Galactus as the new big bad, and successor to Thanos as ultimate threat.
Spoiler Warning: While everything below is theoretical, if correct it will be a spoiler for Doctor Strange. There are spoilers for previously released MCU movies and shows as well.
Who is Galactus?
Galactus, aka The Devourer of Worlds, is a big-time powerful character in Marvel history. He is mostly associated with Fantastic Four team of superheroes. That said, he's encountered the bulk of the Marvel catalog at this point. He's called The Devourer of Worlds because he sustains himself by consuming entire planets to sustain himself. He doesn't do so out of malice, merely survival.
Where Are We at in the MCU?
A lot has happened since the conclusion of Avengers: Endgame. Wanda has grown into a full-blown magical master as the Scarlet Witch since the end of WandaVision. With the Darkhold in her possession, she's silly powerful (you're going to notice this word a bit, wink wink), a true Nexus being.
Meanwhile, on the show Loki, we get a glimpse of how fragile time itself is. By the end of the series, Loki and Sophie encounter He Who Remains, aka Kang the Conqueror. Sophie kills him, setting time off its course permanently. The ripples will be felt everywhere, at all times.
Next, Marvel released the show What If...? It explored events from previous phases of the MCU with minor details changed and the resulting butterfly effect. IE, we were exploring the multiverse. The Watcher narrates us through each episode. Eventually, The Watcher gets too close to the action, ultimately intervening.
Shang-Chi and the Legend of the Ten Rings is released, but I don't see it impacting much outside of being a distraction to Wong, who can't stop Doctor Strange from making a mess in the future.
Elsewhere, a group of immortal protectors called Eternals are protecting Earth from Deviants. They learn their purpose is to keep a planet evolving until it gives off enough power for a Celestial to be born from within said planet. By the end of The Eternals, the group realizes the Celestial's arrival will result in the destruction of Earth. To stop it from happening they band together to turn the Celestial into marble. But is it dead or just dormant??
With the movie Spider-Man: No Way Home, we see the repercussions for Doctor Strange messing with time. A botched attempt to make people forget who Spider-Man is causes a fracture in the multiverse.
Tying in Galactus
If there is one thing that Earth-616 (our Earth) has, it is cosmic power. In addition to everything listed above, you've also got humans, who managed to figure out time travel and reverse the effect of Thanos' snap. We've got Kang the Conqueror coming for a multiversal war on Earth. While we won't see that play out in Doctor Strange in the Multiverse of Madness, we could see him teased as the big bad ahead of Ant-Man and the Wasp: Quantumania. Doctor Strange has contacted Wanda for help reversing the damage he's done. Long story short, there is gonna be hella power brewing on Earth. A perfect meal for a hungry Galactus.
I really can see Doctor Strange in the Multiverse of Madness, Ant-Man and the Wasp: Quantumania, and What If...? Season 02 laying the foundation for Galactus’s arrival. Heck, in the comics, it was a Watcher who first stumbled across Galactus as a new born.
Imagine this as the timeline: the events of Doctor Strange in the Multiverse of Madness open the door for the arrival of Kang. The events of Ant-Man and the Wasp: Quantumania require all the powerful heroes above to defeat Kang. We get a post-credit scene of Silver Surfer identifying the immense power coming from Earth. Thanos-level threat engaged.
Let me know in the comments or on Twitter how wrong you think I am! If you have seen the movie already, don't be that jerk who drops spoilers.