SPIDERMAN: BACK TO THE FUTURE
My theory:
Villian of the week gets tony time tech somehow and blasts spiderman into the past (ideally 80s cos vibes).
Back to the future shennanigans ensue. Tom holland has stated he based his portrayal off of Marty Mcfly so it is perfect for him!
How they go with it depends on whatever the consesus on how time travel works and what its implications is (depends on doomsday basically)
Maybe we get spiderman against old avengers (basically like when we got ant man vs falcon, covertly stealing tech to get back) with him trying not to alter the timeline, and it will be like an action spy thriller. Or have spiderman helping the old avengers with a threat.
It will work really well with the success of the 'what if series', with how theyve set up hank pym (vital for pym particals so he can get back) and PEGGY, Uncle Ben can be a shield member so we finally get the "great power great responsibility moment" (it will just perfectly complete our spiderman without doing the overplayed backstory).
Then when theyre ready to send him back to the future, the fact earth moves through space with time becomes an issue as theyd need a preexisting return point like the 'launch pad' in endgame. So they decide to alter Neds 'find spiderman app' to send out an intergalactic signal (have a funny moment of boomers not knowing how to use phones with hank pym when spiderman shows the app to him) and just send him to a random point in a spaceship.
!It doesnt make sense for anyone to have the that app already and be in space or for that app to have the capability of an entire space gps, which is why i think this theory is incredibly valid, and if its not this ima be upset!
I think we really need an old avengers movie to really move on from the Tony stark avengers to the new avengers.
Then we can get miles morales with spiderman being fully complete ("great power yada yada"), and with one of peters villians wreaking havoc unchecked while peters missing and lost in space, it will be the absolute perfect villain set up for miles.