Yeah, unless the South African government decides to give this thing a financial boost, nothing is going to happen.
That, however, doesn't seem impossible to me. South Africa is enjoying massive economic development and has rightfully earned its place in the BRICS group. They already had the football world championship. Sure, that's a national sport especially of the poor, whereas F1 would be the opposite. Still, of all African countries, South Africa, is, as usual, the best choice.
However, the people who are squeamish about going to Bahrain might also have something against South Africa: the apartheid days may be over, but nowadays there is huge racism against foreigners from the surrounding countries and also equally massive corruption in the ruling party.