About Spiderman... (since only the people we care about were snapped they can use new extras).
I think that this movie wasn’t really the place to explore the new Hulk, but I don’t think there’s much of a change there, really. Bruce has, over 5 years, found a way to be big and green and calm, but we never saw the Hulk really emerge. And Bruce is always full of it when it comes to his relation with the other guy. He’s not some perfect fusion of Hulk and Banner now, he’s just Banner who stole Hulk’s body. And when the worm turns, I think there will be smashing.
Also, personally, I think that Old Steve Rogers is Loki. And here’s why. America’s Ass goes all Doctor Who, fixing the wibbly wobbly timey wimey stuff- which means, at some point, he realizes that Loki is missing. “Great, I’ll dispose of multiple avian beasts with just one rock,” says Captain Time, but when he arrives at Asgard, Loki can sense that Cap has wielded the Mind Stone (also he’s holding the Nexus and Mjolnir), and it’s a dead giveaway. Loki, already seeing things fall into place with Ragnarok and doubting Thanos’ willingness to not kill him, learns from Cap what his future holds, and makes a deal- he’ll provide Cap with a way to live happily ever after without screwing up the timeline, and in return, Cap will help Loki survive Thanos. 2008 Cap would never have agreed to this, but 2019 Cap is carrying the briefcase from Pulp Fiction and has, in the last 24 hours(?) sworn allegiance to his mortal enemies to avoid a fight that he already won once, and punched- and mind-controlled- his former self. Everything he’s ever known has been called into question over 10 years. They have a heart-to-heart about family, honor, and duty, and Cap agrees. When Cap goes back to meet Red Skull about a Soul Gem (and punches him, out of force of habit), he trades “a soul for a soul”- bonding Loki to the Stone, before they’re ever used. When the stones are used by Hulk, Loki is un-killed along with the Snappening victims and disguises himself as a random Asgardian in the chaos. He attends Tony Stark’s funeral in the guise of that kid from Iron Man 3, and relays what happened to Steve Rogers, as Steve Rogers (notably, one of his favorite people to impersonate). And where’s our Cap? In another universe, where Steve Rogers never survived in the ice, filling the void that his alternate self left behind.
It’s a stretch, but I reeeeaaaaally want Loki to still be alive.