It would have to be a new shard. Only problem is that would have to be our largest expansion yet because it has to do:

an updated hall of novice
Branching storylines for people who have done the previous story and those who are new.
Complete introduction of existing systems that already exist in the game and roll them out at a not overwhelming pace.


Basically it is better to just improve the current leveling system and jobs to make early game more fun than it is to create a new starting point