I must say I was a supporter of the idea of concurrently running worlds with the current world existing permanently, or at least for prolonged period.
In my perception running parallel world with adjusted parameters like defined world lenght, win condition, or simply adjusted world speed/resource availability parameters could be a source of players for a persistent world, e.g. groups and villages formed in temporary world might decide to move their community to persistent world where things run smoothly and permanently.
I even considered for myself join or even form some big village accepting anyone and just have fun instead of hermit-sweating my stuff.
Overall I see a lot of different indie projects now that restart worlds of this projects, like Foxhole where war restarts after win condition is met, and on new war in few days people start with unique war conditions (availability of resources, map layout and win condition), starting without any technology discovered or industries built.
Although, I now have to admit that the idea of parallel world at this stage will leave current world absolutely uninhabited, as there's way too few people left playing and with no objectives left.
It's sorry to admit but if new world happens any time soon, there's no other way to go other than wipe current.