If I may.
Where are all these 'black nationals' you are speaking of in South Africa?
If they do not get sponsored - they do not enter the aviation game. Many that get sponsored, either fade away during training, or stick at it for a year or two before deciding they are not really that interested. A small handful push through and make a great success of it.
The problem in SA, is the flight schools pumping out thousands of shiny new comm pilots every year - with no real chance of meaningful employment.
The biggest hurdle to getting a flying job in SA is that the traditional bottom rung - commercial piston flying - has all but dried up. Entry level has become light turbine.