Well, that job list was intended to get every FF job into the game. I don't think it was intended to be really feasible.
Well they're missing a lot of jobs if that was the case. Some are small ones, sure. But others have been sufficiently big to deserve spots on the list, especially if they're going to be tossing in obscure ones like Necromancer (when was that ever a job???).
Personally, what I can see happening is the creation of sub-item classes. Say, a scope. When you equip a scope on a Gladiator, you gain the ability to learn Blue Magic, but lose all shield skills, and some of your other glad skills. When you equip the scope on an Archer, you can specialize as a Sniper. Etc.