It tips commodity-rich Russia and Australia to benefit.
Chief economist and partner Savvas Savouri, who has been researching South Africa's economy, cites emigration of professional workers and what he sees as a "lack of centralised leadership" when it comes to dealing with problems such as the Aids epidemic.
"It's socially, politically and demographically flawed. It will malfunction within 15 years. It will go the way of MENA (the Middle East and North Africa) but the blow-up will be much more serious," Savouri told Reuters in an interview this week.
"Professional whites and blacks are leaving in hordes - the human capital is decaying," he said.
Savouri's comments come as Libyan ruler Muammar Gaddafi struggles to contain a two-week-old popular uprising in the world's 12th-largest oil exporter, which has helped push brent crude above $115 a barrel.
The unrest across North Africa and the Middle East has also seen the ousting of Egyptian leader Hosni Mubarak and Tunisian leader Zine al-Abidine Ben Ali, as well as protests in Bahrain and Saudi Arabia.
Savouri said a "malfunction" in South Africa, which is the world's biggest producer of platinum and a major producer of palladium alongside Russia, would push commodity prices higher, benefiting rival commodity-rich countries.
"Clearly Russia and Australia will win out. The surge in commodity prices will benefit them," he said.
Savouri, who is known for being outspoken in his predictions, said in January that the financial services industry was practically "lawless".