Probably depends on many things, including what your carnet issuing AA will require for returning the bond. I hope I´m wrong, but if the vehicle stays in RSA, and you go back home, then you might have some trouble getting the bond back (...I´m really not sure, if I´d try this in my country!)
At the very least, your carnet needs to be stamped out by the customs of every carnet country, that it has visited.
The carnet system exists, because some countries do not want to you to bring your vehicle there permanently (without paying their considerable taxes & duties). And if they think, that this has happened, they´ll make a claim for all these to your carnet issuing AA, who will then need to be able to prove, that the vehicle is not in that country, that made the claim. So if you return without the vehicle, expect your AA to be very suspicious.
But maybe somebody will have better info on if there is a way around this, or if it makes any difference if you´re selling it to another person, who does not plan to keep it there.
Here might be something useful: