Seems to me they will first work on one job for each class, and then grow from there. Most likely this would mean multiple classes can choose from multipe jobs.

I could see:

Basic Jobs:
Requiring only 1 class, but Job could be used on all applicable weapon types.

Monk
  • R30 Pugilist

Warrior
  • Marauder
    OR
  • Lancer
    OR
  • Gladiator

White Mage
  • R30 Conjurer
    OR
  • R30 Thaumaturge

Black Mage
  • R30 Conjurer
    OR
  • R30 Thaumaturge

Thief
  • R30Gladiator
    OR
  • R30Pugilist

Ranger
  • R30 Archer
    OR
  • R30 Musketeer

Advanced Jobs:
Requires single higher level class or multip classes.

Paladin
  • R30 Gladiator
    AND
  • R30 Conjurer

Dragoon
  • R45 Lancer