Olzhyria(south) with the Gha Naboh Matriarchate, the homeland of mithra. Things known about it:
- Giant beasts live in the wilderness
- The mithran queen is a ***(Lekho hints she is evil)
- Law is cruel(Sin Hunters)
- Yhoh should be the capital of Gha Naboh
- At least the islands of Tsahya and Zhwa are under Aht Urhgan's dominance
- The royalty probably hails from Zhwa
- It is unclear whether it's three different nations or not, but Gha Naboh, Zhwa and Tsahya seem all equally important
Far East:
- An empire that's been at war with Aht Urhgan for many years
- They greatly suffered the effects of the emptiness
- Phoenix is in a sense their guardian(I would in a relationship akin to Fenrir-Windurst, with the exception that Phoenix is nicer)
- The yagudo homeland is here as this is the seat of the shogunate
- It is unclear whether the yagudo nation and Tenzen's are only one, but it's safe to believe it's two different one
- They helped the mamool ja in the war against the empire
- Bushido and ninjutsu were invented here
Razhowa(north):
- Homeland of orcs and gigas
- Orcs burnt to the ground one of the Yggdrasil twins
- Runes were first discovered here allowing the birth of rune fencing
Now, new jobs seem extremely unlikely, but if they were to add some, which could it be?
- Necromancer(from the south; the mithra race has a sort of morbid relationship to the concept of death and respect for the dead) pet job that uses undead and demons(they wanted to release it back with AU already, so the concept exists)
- Chemist(far east?) A class that can make meds a bit more relevant wouldn't hurt
- Morpher(south) Hybrid class that could cover a variety of roles taking the form and thus abilities and stats of monsters(somewhat redundant with bst)
Anything else: sorry bro, but nope, we already have them in game. But like I said, any new class is very unlikely, so let's just hope for the lore and the areas to be released. An expansion doesn't need new jobs necessarily.
Source: I'm a FF scholar.