The only things that would return would be universals, like Nuka Cola, power armor, and vaults. No old factions or characters. No enemy types except those that should be everywhere, e.g feral ghoul. Personally I think deathclaws shouldn't be everywhere, but I can see an 'invasive species super-apex predator blah blah blah' argument coming so whatever. Though I will say that an original megafauna that could hold their territory from deathclaws could be cool. I also suppose raiders should still be Mad-Maxian, but I don't see why a fresh take on them wouldn't work. Ostensibly if we did get to visit Legion territory as was planned, presumably the only raiders there would have been the Legion, and non-generic raider gangs are definitely better imo.