I like your Steve Rogers comment. It would be particularly apt if the multiverse is indeed collapsed and they end up living on the main Earth. It would even be more interesting if they end up living on the main Earth and the rest of the world knows who they are and believes they've been living there for years.
As I've sat with the film for awhile, I really think it's one of the best MCU stories we've had in years. I think I like Thunderbolts just a little bit more, but that still makes two great stories in a row. My wife and kids thought it was great and they haven't liked a Marvel film since GOTG3. I hope that the FF get a sequel film after Secret Wars without too much delay.
The multiuniversal squash had everyone in 616 believe that Miles Morales Spider-Man had always been there but even if that happens for Marvel's First Family... They are still from the past.
The jew issues (wow, I'm going to leave that typo in, I'm typing on my phone.) of Captain America are set in a spongy era of the 60s/90s just 7 days after the Avengers revived Steve from the ice... So he's still going on missions for the Army (General Ross!) and they have current heretofore unheard of Captain America of the 60s/90s who is not Nuke, as Steve Roger's babysitter.
Even if this Fantastic Four from the new movie, is from a parallel world, maybe movie 616 has its own Fantastic Four who are pushing 120.
Ben and Reed, seem immortal?