Most recent thoughts were to fill in old stuff, mainly where Achievements are/start at.
With the Hunter back filling it would be easier to go back even further, but Quests aren't as easy since stuff that old generally doesn't use the Quest Window and that, so it gets harder to like start-end set up quests and requirements on further ones in a quest chain.
No ETA on any of this though, Old Content isn't as big with well established stuff already existing, it is something we want to back fill eventually for completeness though.