They've already mentioned more than a few times that after the game is stable, post 2.0 release, they're going to start creating new caster jobs to balance the DoW/M ratio. I would assume they're thinking of maybe putting Arcanist in? Don't know what its identity would be, though, it's sort of a customs officer in the lore atm.

As such, I don't think Time Mage is a stretch, neither are jobs that are similar to Geomancer, Mystic, Blue Mage, and, of course, Summoner.