Spider-Man: Far From Home - What Does The Multiverse Mean For MCU?
3. Bring In Fox Characters
Ever since the MCU proved just how successfully it could do Marvel characters, there's been a desire to see the X-Men and Fantastic Four (and the various villains who come with) in the universe, especially in recent years as Fox's output has taken a serious downturn.
That wish is now just about ready to be granted, with Disney purchasing Fox and, with it, those characters. It'll still be a few years yet before we have the likes of Wolverine and Mister Fantastic in the MCU, but now at least there is a definitive means of doing it.
So far, there's no sign of mutants in the MCU, nor of the Fantastic Four. But that doesn't mean they can't already exist in another dimension. If the gateway to the multiverse has opened here, then it could do so again, and it'd mean you could then introduce those characters as being from a different dimension and fold them into the mainline MCU (because ultimately, people want to see them interact with other Marvel characters). That goes for major villains too, such as Doctor Doom or even Galactus, and could give them new threats to play with later down the line. It's the easiest explanation for where they've been, and thanks to Endgame and Far From Home it's already partially written.