The Job Quests tend to all have a solid ending to them. If anything, they would probably end up being completely new story arcs. However, it is also possible that the NPC trainers from the original Job Quests end up returning, or the Job quests happen with new NPCs, but it is the Soul Crystal itself that grants the knowledge of new abilities rather than some NPC.

I am honestly very excited for what 3.0 will bring!