On an opinionated note. No, I don't want to see Thief OR Ninja in any capacity in XIV.

On a logical note based on the development of the game: we need at least one or two more mage classes, a ranged, and one or two pet classes.

Suggestions:

Arcanist/Geomancer
Mystic/Time Mage
Sage/Summoner
Flayer/Beast Master
Musketeer/Gambler

Above all, I'd love to see a non-melee Blue Mage.