Now that they're available to replay in NewGame+ it's a good time to encourage you (and really anyone else) to replay the Conjurer quests. The entire basis of the class is that they pull the energy from the earth to cast elemental spells and heal, and the elements they use are exactly the elements that the geomancer uses in the astrologian quest. So the problem for geomancer right now is that, like with other jobs, it steps on the toes of other job identities, like how even though we saw a berserker in the new dungeon, we probably won't ever get one because that's just an central aspect of the warrior job identity.
Which leads me to the point of necromancer... the job has only ever been in one game. Final Fantasy V, and to that end was basically an undead blue mage - black mage hybrid. This could go either way. It could be an opportunity for Square to decide what they want the job to be, but my opinion, it's more likely they just don't add it due to the cultural implications in some regions as well as the only identity it does have is already in the game on a limited job.
Apothecary I'm hoping was a legit tease, but as always I'm waiting till I have something more firm in the game or from the developers. Though I will say this is a better tease than geomancer was considering I don't put too much stock into what enemy types exist, and geomancer existing only in the, at the time, highest level job quests isn't a great place for a teaser since unlike with this tease, not ever player would have interacted with it.
Astros already have the time mage stuff covered. Though that's been getting stripped from their identity. Go to Central Coerthas and the astrologians in the observatory there are even dressed as classic time mages (purple robes and sugarloaf hats with stars on them) So it's a problem again that time mage alone doesn't have enough of an identity to stand alone as a job in this game. It would have to have something else to it beyond time manipulation to make it work in the strict tank-healer-DPS meta of the game, and it would have to do so without taking from the identity of astrologian.