Heres what I was thinking for new jobs.
Red Mage - Buffer, and Regen/Shield healer (use shields and regen to keep tanks and dps at full health)
Ranger - Uses a rifle, one with animals/beasts/monsters of eoreza and able to tame them to fight side by side.
Beast master - This one is kind of different, transforms into different beasts, being a healer, dps, or tank.
Samurai - Idk, Ive always pictured Samurai as DPS and not tanks. but as DPS sam would be easily implemented into the game.
Dark Knight - Now I was thinking DPS then I thought about (don't kill me) Blood Death Knights from WoW, and thought we could make Dark Knight into a Tank
This is it for now, Please feel free to discuss, add jobs you think would fit. and why.