Dancer
Rune Fencer/Knight

If Stormblood is anything to go on, I feel it's all but inevitable they add Blue Mage and Dancer due to their respective popularity. Granted, they did mention wanting to create a job wholly unique to FFXIV. A greater concern is how they implement new tanks and healers. I'd like the next healer to have some greater degree of creativity put in. Astro essentially functions as WHM/SCH with cards.