Would love to see THF make an appearance again, and it probably will, but who knows. Aside from that I really hope for Chemist and Mechanic or something like that, I mean I love several of the jobs in XI, but I want something new.
All they really need to do is look at FF Tactics. That three-game series has a total of about 100 jobs across it.
I've also always wanted to play chemist. Using consumable items for healing, changing them into poisons for attacks; using abilities to turn them into buffs - it would be great fun. Chemist would be a perfect job to use in conjunction with alchemist, which could supply it with various items, and chemist itself could make its own untradable "temp items" to prevent it from becoming a job that demanded too much financial support to be feasible.
Oh, well, at least I got Bard; I'm super excited about that. Now I just hope it plays like a total support class (like FFXI) instead of the button-spam combo-point DD-hybrid whose abilities grant buffs automatically like in so many other MMORPGs. The latter isn't really a Bard, it's a Rogue who whistles sometimes.