Did anyone work out how map-hopping would work in a multi-player environment?
I've given it some thought...
Blood moon zombies, specifically, have a chance to drop a 'rescue' quest note. On activation, this quest picks a random area on the map to be the extraction zone and starts a timer. When the timer expires, anyone standing in the extraction zone is 'rescued': they are whisked away to the new map, accompanied by any cutscenes.
Players in the extraction zone spawn together in the new world with their tool belts intact. Players not in the extraction zone at the time are not rescued and thus 'don't make it'. This is presented as a failure state. They spawn into the new world away from the others, with no clothes or tool belt, as if they had died or assumed a new character. Thus there's an incentive to kill lots of zombies on horde night, loot the corpses, and reach the extraction zone in time to avoid a kind of death penalty.
In PvE, you could agree to do the rescue quest when everybody's ready for something new. You can work out people's roles so they can bring the most important stuff, and get to work right away tearing into the new world.
In PvP, you'll want to kill and loot as many zombies as possible in hopes of getting the rescue quest yourself. Let's say everybody can see the extraction zone & timer once activated. You can try to trigger the extraction at the most inconvenient time for others. Everyone can sprint to the extraction zone and attempt to defend it until time runs out: a King of the Hill battle royale. Since you don't know where the extraction zone will be, you can't set up defenses beforehand. Though I prefer PvE, I think it could create some pretty epic endgame brawls.
I'm not sure what to do about players not logged in when extraction time hits. They'd be unhappy to lose all their stuff, but you can't protect them either or they'll log out on purpose. If people were
really open to outside-the-box ideas, the players being extracted could split off and actually join a different server, but I doubt it would actually come to pass like that.