im wondering how realistic an idea it is to recreate a world like forgotten realms and allow people to script stories as modules.
partly for the classics and partly for the huge amount of fan made content already in existence.

could also be applied to plenty of other worlds

Being able to do so is the whole point of making the editor public, I think

im meaning more the idea of layering stories in chapters so people can extend each others stories in a way but happening in the same place

in short, quest exp and balance.
Story is easy to extend, but balance side for a continuous growing project is a bitch.
Too much side quests and you over leveling, only story no quest people would rather read a novel piece. Yeah, so it's only a matter of time there are going to have level scaling option for mod as well, people hate it for campaign, but community project is okay.