I think what will eventually happen is that there will be so much turmoil that the place will undergoe a revolution, giving the Marxists the complete power that they have strived for in that country.
The Marxists are already in charge, any semblance of moderation is pure window dressing.
The Safricans I worked with in eastern Africa all feel what you mention will happen after Mandela dies. There is a lot of fear over the future among both the black and white population.
Too bad, it has the potential to be a great country.