Guandao
Rajah of Minyue and Langkasuka
Because every Southeast Asian civ added is taking the place of a Middle Eastern or Native American civ that could have been added.
I don't think they are taking places from the Middle Eastern or Native American Civs. How many more Middle Eastern Civs will be added? Babylon, Ottomans, and maybe a third one. I'm betting on only 2 North Amerindian Civs in Civ6, only you are referring to all the Amerindians including the Maya and the Inca.