Here's a way to think of it, the way I understand it. It'll essentially be a "spec" system like most MMOs have now. Where let's say you have 3 jobs to unlock, those 3 jobs would function as three "skill trees" where you spec into one for a specific benefit or role. For instance, gladiator may have Paladin, Thief, and Red Mage. Paladin would be tank, Thief would be melee damage, and Red Mage would be spell damage. This is the way I understand it, and the way that makes a good deal of sense.