They already said they didn't like how SCH/SMN turned out, and it's easy to see why because it's difficult to tweak one without affecting the other. Based on their strategy in HW I think they're done with having branching classes, despite it being a cool concept.

However... if you ask me, the most logical branch for CNJ would be GEO as a DPS. They added one tank/healer/ranged phys DPS in HW and NIN was added recently too, so it's about time for a new ranged magic DPS.

Also, before adding any new healers the development team needs to rethink their vision for new healing classes in this game because AST was kind of a lackluster addition honestly. Take away the card mechanics and they're a gimped WHM.