Here's a question for you: why is Scarlet Witch in Doctor Strange 2? Here's another: why is Doctor Strange 2 linked to WandaVision? And here's a third: why are we getting the multiverse introduced now when Spider-Man: Far From Home seemingly killed its importance to Phase 4?
Well, what if I told you that Scarlet Witch's entire MCU arc has led us to this point, where she is the key to bringing mutants, the Fantastic Four and all other manner of multiverse-dwelling characters into the main MCU timeline? What if her weaknesses will be tested once more and this time she can't control it?
First a TLDR version of this theory... In Doctor Strange 2, Nightmare will draw Scarlet Witch to the Dream Dimension by promising her a life with Vision, where he will weaponise her to help him take over the multiverse, causing a catastrophic event that tears the multiverse open and is linked directly to WandaVision. Now let's talk about how we get there.
4. The Multiverse
While Mysterio's claims of being from "another world" in Spider-Man: Far From Home didn't quite prove to be the catalyst for the MCU Multiverse opening up as we all suspected at one point, there's no doubting that it does still exist.
For Endgame's time travel-infused ending to work - and indeed the entire plot - the multiverse has to be behind it and that's not to mention the explicit nods to it in Thor: The Dark World and Doctor Strange as well. It's just that, as far as we know right now, the gates to other alternate dimensions remain closed.
After all, that is Doctor Strange's job as the Sorceror Supreme - to maintain vigilance against threats to Earth from the multiverse. Like Dormammu, for instance. Or Loki. But not Loki that other time he invaded with the Chitauri, for some reason...
Anyway, that defence element is pretty key, because it could prove to be the driving force behind the plot of Doctor Strange In The Multiverse Of Madness. Because there can surely only be one reason Strange would leave his post on Earth and head into something as ominously titled as an actual Multiverse Of Madness: a credible and immediate threat to the universe.
And given the rumours of the debut of another Doctor Strange villain in the sequel who has very specific links to an interesting part of the multiverse, there may be some clues as to what that threat might just be...