On that note, it has to be said at least once per topic that a map editor/creator will be released soon, so there will be a pretty good amount of user-generated content in the near future as well.
It looks like the developers plan to expand the game outwards a large amount looking at the map included in the game. Right the series is only this one dungeon.
Well, sorta - that map is just kind of a fluff deal, to give you a feel for how big the outside actually is. Right now they're working on out on a minor bug hunt, but their main goal is getting a functional map editor out as quickly as they can. The initial release isn't planned to be much - just a basic layout and placement deal, so people can get started on whatever they like. After that they'll work it up to a full-fledged world editor with scripting and such with gradual updates.
They have said they'll likely make more "official" dungeons themselves as well, so that's probably what they'll shoot for eventually.