I think the next two jobs will be a magic DPS and a melee that shares gear with Ninja.
For the mage, I still hope for Time Mage with a big focus on DoTs, while SMN focus would be on the pets.
For the melee, I think they will make up a new job name while still taking inspiration from an existing FF character (like they did with Gunbreaker and Reaper). My bet would be on Seven and her whip-blade from Type-0.