I think there's no need for country change as Native American tribes, but I would like to see a possibility of changing religion so that Christians can no longer seize my territory after succesful westernization. A good idea of this is in the Divide et Impera mod, where pagan countries can later convert to Reformed Pagan and their provinces cannot be seized.
In my mod, I've changed the files so shamists cannot change culture through conversion, and so all animists, outside Central/South America will switch to shamanists after conquest by others. It reduces the issue to just those cultures which the rule had in mind.