I've made my own list too!
Canada I would love to see; and would be a great candidate for 2 Leaders; the French one should get bonuses to joint wars resembling the French recruiting the natives to assist them in the war. Lady Six Sky would be great female representation for the Maya, Charles/Karl XII would be great to see for Sweden and Mali would be fun too as a economic power house. New Civs I think could come in the form of Canada, Haiti (or Caribbean), Chola (if we've not had enough India already) and Pagan!
Civ6 Expansion 2 hopes and predictions:
Leaders & Civs: Lester B. Pearson (Canada), Samuel de Champlain (Canada), Toussaint Louverture (Haiti), Lady Six Sky (Maya), Pachacuti (Inca), Charles XII (Sweden), Boudica (Iceni), John IV (Portugal), Franz Joseph I (Austria), Constantine (Byzantium), Suliman (Ottomans), Sennacherib (Assyria), Idris II (Morocco), Mansa Musa (Mali), Ezana of Axum (Ethiopia), Rajendra Chola I (Chola), Anawrahta (Pagan), Kamehameha (Hawaii)
Natural Wonders: Cappadocia, Victoria Falls, Lake Baikal, Mount Bromo, Mt Fuji, Diamond Head, Blood Falls
Mechanics: World Congress (WC for Tier 2 government Civs), United Nations (WC for Democracy Civs), Socialist Union (WC for Communist Civs), Military Axis (WC for Fascist Civs), Natural Emergency (Flooding, Earthquakes, Eruptions depending on map features), Pandemic Emergency (Plague and disease caused by trade routes, settling foreign continents, starvation, units killed and war)