In my opinion, there is currently still plenty of room for new civs, as there are still plenty of 'deserving' candidates out there with the possibility of interesting new gameplay styles. It does make deciding on just 9 rather difficult though. Here are some that I think could be possible choices, or at least dark horse candidates (the boldness of the text indicates a combination of very roughly how likely/worthy I think they are of a spot):
Europe: Hungary, Bulgaria, Kievan Rus'/Ukraine, the Goths, Gaul, the Franks, Switzerland, Italy, Minoans, Serbia, Belgium, the Czech/Bohemia, Scotland, Ireland, Norway, Finland, Lithuania, Romania, Croatia, Albania, the Teutons/Suebia/Germania, the Iberians (ancient), Dacia, Etruscans.
Middle East, North Africa and West Asia: Sumeria, the Hittites, Armenia, Israel, Phoenicia, Yemen, the Indo-Greeks/Seleucids, the Khazars, Parthia, Khwarezm, Egypt (modern), Iran, Libya, Tunisia, Syria, Georgia, Aramaeans/Palmyrene Empire, Palestine/the Philistines, the Vandals, the Hurrians, Lydia, Lycia, Oman.
South and Central Asia: the Mughals, the Tamil/Chola, the Kushans, Harappa/Indus Civilization, the Scythians, Bengal, Nepal, the Kazakhs, the Timurids, the Uzbeks, Vijayanagara, Siberia/Sibir Khanate, the Hepthalites.
East and Southeast Asia: the Khmer, Vietnam, Tibet, Burma, Champa, Malaysia, the Filipinos/Philippines, the Manchu, the Uyghur, Baiyue/South China, the Ainu, the Xiongnu, the Göktürks, Laos, Nanzhao.
Australia and Oceania: Australia, the Aborigines, the Maori, New Zealand.
Africa (sub-Saharan region): the Kongo (+ Angola/Ndongo?), the Swahili, Nubia, Mali, Zimbabwe, the Yoruba, the Hausa/Fulani, South Africa, Nigeria, the Ashanti/Akan, Merina/Madagascar, Uganda, Somalia, Djolof, the Igbo, the Xhosa, Kanem-Bornu, Kenya, Tanzania, the Mossi, Luba/Lunda, Wagadou.
North America: the Inuit, the Cherokee, the Sioux, Canada, the Mississippians/Cahokia, the Pueblo, the Haida, the Apache, the Navajo, the Ojibwe/Chippewa, the Seminole, the Creek/Muscogee, the Choctaw, the Huron, the Cree, the Algonquin, the Tlingit, the Paiute, the Nez Perce/Niimiipu, the Illinois, the Cheyenne, the Crow.
Mesoamerica and the Caribbean: the Olmec, the Tarascans/Purepecha, Mexico, the Zapotec, Cuba, Haiti, the Arawak, the Mixtec, the Totonac, Jamaica, Guatemala.
South America: Argentina, Gran Colombia, the Muisca/Chibcha, the Mapuche, Chile, the Chimu/Moche, the Tupi/Guarani, the Chachapoya, Peru, the Wari (Huari), the Nazca, the Quimbaya, Ecuador.
I don't think that all of these civs will (nor should) be included, but even with just some of the more likely candidates there are plenty of good choices remaining.
New Korea could be led by Kim Jong V (as in the 5th), and feature music from actual N Korean propaganda songs. Just something different to hearing the same old candidates floating around!
