Well first of all the scuttle but I've read suggests that SA has been fudging their reserves and their pipeline capacity is maxed out at the present rate of production.
The SA oil ministry has also come out and admitted that their is nothing they can do to lower oil prices which is code for "we can't increase production". So $45 to $50 oil is here to stay.
Secondly the SA reserves are sweat crude while the oil sands are heavy oil which is not suited for gasoline refinement.
It's more suited for bunker crude products, home heating oil as well as greases and petrochemicals.
I think that the fundamentals for heavy oil are going to continue to be strong over the long term.
I don't think that SA is in a position to manipulate prices anymore unless they're hiding reserves which I seriously doubt.
I don't have any insight into the SA reserves, but I suspect they have much more than they are admitting to. Our geologists have been helping them for years, (I don't know whether they have learned enough to eliminate the need for our support) but we used to read about reserves that extended into 10s of years from now. Who knows? I guess we will find out if oil drops down to $20-30 a barrel again?
I agree with you about the light sweet crude vs the heavy stuff we are pumping in Texas and could extract from shale or sand. There is of course more oil coming online in Russia, and SA's market share is dropping, so maybe your scuttle-butt is right. But oil price still will fluctuate and have the result that high priced operations are driven out of business.