I personally wouldn't mind seeing more jobs do as Arcanist did, put Theif under Rogue, Ranger under Archer, Geomancer under Thaumaturge, Beastmaster and Berserker under Marauder, or make new classes for the existing jobs that don't have them, like a Ward or Apprentice for jobs like DRK and AST.
Also, I know it's a bit of a stretch, but make jobs interchangeable inside dungeons/instances, they could tinker with a lot of dungeon mechanics by doing this.