For me it's great news that Portugal won't be in this expansion. This means we will get it later - hopefully packed together with Kongo
Besides the known 30 civs, this is my preference list, and my guesses for the expansion civs:
The last 4 remaining places in the expansion:
Hungary or
Poland,
Ethiopia or
Zulu,
Sumeria or
Hittite,
Sioux
Portugal + Kongo double pack as DLC
Besides these, 1st tier civs (should definitely included eventually): Poland or
Hungary, Zulu or
Ethiopia, Hittite or
Sumeria, Phoenicia
2nd tier (also great additions): Assyria, Nubia, Sweden, Bulgaria, Khmer, Mali, Moors (Al-Andalus or Morocco), Indonesia (Majapahit or Srivijaya)
3rd tier (a couple from each region would be nice if there is still room): Apache, Comanche, Navajo, Inuit, Mapuche, Guarani, Arawak, Tupi, Swahili, Zimbabwe, Benin, Vietnam, Burma, Austria, Bohemia, Lithuania, Kievan Rus, Khazar, Mughals, Scythians, Timurids, Huns
I know there are also a lot of suggestions for Israel, but in my opinion the perfect representation is to have Jerusalem as a religious city state