Content

It is possible to have content that is never experienced on a particular server, but there are other ways to introduce the content if it is just 'tied to a particular level of node'.

Node types are static and decided backend by the developers, so, yes, they are presets.

Unless all the servers across the world follow literally the same path of node development, I'd say that kind of situation is impossible. Now obviously you as a player will definitely not experience all of the content that the game will have, and you'll have to come to terms with that.

But on the grander scale, I'd bet all content will be experienced by at least someone. And then that person can tell others about that content and, if others are interested in it, they can work together to develop the node that provides that content. And that's the potential fun of the node system (at least as far as I understand it).