Spider-Man: Far From Home

Hence Tom Holland's warning at the beginning of the trailer.

That trailer is insane.

My thoughts on the trailer -

Spider-Man: What about Thor?
Fury: Off world.

Spider-Man: Captain Marvel?
Hill: Unavailable

Spider-Man: Daredevil?
Fury: Cancelled.

Hopefully it's something like this, because if it goes the obvious route, I'll be a little disappointed:
That Mysterio is just a bad guy pretending to be good, and the one creating all the monsters to begin with.

What disappoints Fannible is everything I want to see.

But that’s what we all expected from the original trailer: Mysterio creating the Elementals. But if Sony gonna whip out the Spiderverse (and link it to post-Endgame MCU) they gotta make all this more interesting.

I reject your notion of interesting and demand my safety net.

Wyldstaar, get your butt over here. So how would you feel about Scarlet Witch becoming a villain (based on the House of M comic) and changing reality to include X-Men and Fantastic Four. And... maybe... maybe... Mysterio IS a villain and he is from the multi-verse BUT he's a mutant.

It feels like with the end of the last one, and Mysterio here, they're building towards a Sinister Six.

I wouldn't like it.  I never really approved of the House of M or No More Mutants.  No one character should be able to wield that much power naturally.  In the case of the MCU, I don't think it's much of a possibility.  The MCU version of Wanda has never displayed reality altering powers, only telepathic and telekinetic abilities.  It's possible that additional aspects to her abilities will be displayed at a later time, but even then, probably not to such a radical extent as altering the history of the entire planet.  Even when Thanos acquired the Reality Stone on Knowhere, the changes he made all reverted back to normal as soon as he went away.

I don't think that any changes to the MCU are necessary to bring the Fantastic Four in.  At some point in the 1960's, Reed Richards and Ben Grimm are allowing Reed's grad student Sue and her little brother Johnny to join them aboard their prototype rocket during an engine test.  A saboteur from Latveria has reprogrammed the ship's systems to overload the engines during the test.  The ship's instruments alert Reed to the problem, and he's able to avert an explosion by launching the ship.  As a backup plan, the saboteur has locked the ship's guidance systems towards a spacial anomaly, which grants them all elemental powers and takes them to the Negative Zone.  After having a trilogy of adventures there, Reed figures out how to return to the MCU, and the FF find themselves in the year twenty twenty-something.  

Mysterio is a perfectly good character already.  He doesn't need to be a mutant.

As for the X-Men and mutantkind in general, that's a tall order.  It's going to require a major alteration of the MCU in order to make the slightest bit of sense.  While I'm sure he has a few ideas, I doubt Kevin Feige has decided how he's going to do it, yet.