My reworked list, taking the leaks into account.
Confirmed:
1. Korea
2. Netherlands
3. Mongolia
Leaked but unconfirmed:
4. Cree-this will be our only North American representative in this expansion. Sorry to the Canada fans!
Unconfirmed:
5. Georgia-they are hinted at in the trailer, with the Mongols attacking a Georgian fortress, and Tamar is a good female leader choice.
6. Italy/or Italian City-state like Genoa-the Absence of any Italian CSs in Civ6 makes me wonder, and they are seemingly hinted at in the trailer (plague doctor, perhaps the exploration).
7. Inca-since Firaxis made a big deal about representation, I'm expecting the Inca to represent South America. Perhaps the lack of Machu Picchu wonder in this expansion is due to difficulty making it a wonder on Mountain tiles? Or maybe Firaxis listened to Siptah's criticism of Machu Picchu as a wonder?
8. Ottomans-the Byzantines seem less likely with Antioch as a CS, there's no hints to them, but Janissaries did appear in the Polish scenario, so the Ottomans aren't too far off from becoming a Civ.
I think Africa won't get a Civ this expansion, because of the Nubia DLC (basically what Eagle Pursuit said).
Portugal is probably being saved for the next expansion or a DLC. Same goes for the Celts. Having both Georgia and the Ottomans in the expansion might seem like that region is being over-represented, so either one of those might be replaced by some other Civ. Carthage seems less likely since Hannibal Barca is still a Great General.
Alt Leader: Chandragupta Maurya of India
Conclusion: I'm expecting at least one more European Civ. My guesses for the unconfirmed Civs can be all completely wrong.

I'm actually expecting at least 4 female leaders. We have Korea, Netherlands, Georgia, and......I'm not sure who the fourth leader would be, either Italy or the Ottomans?