South Africa won’t have to foot the bill.
The situation in Zimbabwe will grow so horrible that the international community, UN, and idle rich everywhere in the West will throw (mostly taxpayer) money at South Africa for “rebuilding” Zimbabwe.
Angola (oil!) and Sierra Leonne (diamonds) are in a similar position, though not quite as extreme.
Playing the right geopolitics, a South African leader could gain international support for expanding SA control into all of the above, plus Sudan.
Yeah, South Africa really could take over (most of) Africa.
Of course, South Africa would have to act before SA itself melts down (its own land “reform” ideas will put it into Zimbabwe’s place in another generation)...but the money pouring in to its privateers (SA is big on providing private security, especially in Iraq) could do it.
Points well made.