Nelson Mandela had no misconceptions about what would happen in a South Africa without whites; never mind the bloody disasters from decades before (Katanga secession in the Congo, Biafra secession in Nigeria) - he was watching Zimbabwe (turned over to black rule in 1980) disintegrate before his eyes. He pleaded with whites not to leave, as they would leave the country without doctors and other professionals, and granted concessions to help retain them.
IIRC Mandela originally was a fierce Anti-Communist, but the Soviet Union made Mandela and the ANC an offer they couldn’t refuse.