I ride with the late Dr. John Henrik Clarke on this issue; he stated that Africa should be under African governance, and anyone who has an issue with African governance over Africa should be shown the air strip, the shipyard, or the graveyard; cuz they got to go.
We see that even the regions that are absent any non-Black presence are still governed by neo-colonial policies; so the absence of colonizers does not mean the absence of exploitation and colonial domination.
I don’t think it’s unrealistic to have an African nation, or African Continent free of all non-Africans, because like Garvey stated a century ago; “we can accomplish what we will.” Also, as you stated, the Ethnic Cleansing of all non-Blacks from Africa would constitute a genocide. We are quite familiar with this in the African Diaspora because Black populations have been purge on community, regional, and national levels a number of times in the US and other nations with large Black populations.
The good thing is that purging Africa of all non-Black inhabitants is not a prerequisite or even a necessity for Africa’s unification and liberation; but Africa for Africans, African governance of African land and lives is the goal; and anyone who opposes that forfeits their right to dwell on African land.
Historically, African has not been a xenophobic land, there were some nations that shunned foreigners, but there were just as man that were open to outsiders, too open in fact.
Finally, think Africa’s relationship to the descendants of invaders and colonizers needs to be informed and guided by our history, first and foremost.