A possible Greek exit from the euro zone is not, obviously, a new concern. Three years ago, it looked like a realistic possibility until Berlin became convinced that the risks of contagion for other euro-zone countries was too great. But since then, the situation has changed dramatically. Both Greece and the euro zone are in better shape than they were in 2012 and would be better prepared to handle a Grexit. Still, Greece's departure from the common currency union would almost certainly be more problematic than Schäuble has made it sound. Josef Ackermann, the former head of Deutsche Bank who led the debt haircut negotiations in 2012 on behalf of Greece's private creditors, continues to believe that a Greek exit "is still a very risky proposition. It would very probably lead to bank insolvencies and enormous social costs in Greece."
Euro-zone countries may have established a functioning bailout fund and made progress on a banking union scheme, but a Greek exit could attract speculators. "International investors would quickly begin asking which country might fall next," Ackermann believes. Markets could gain the impression that the currency union is a club that countries could join or leave as they liked.
Speculators could begin testing just how durable the rest of the euro zone really is and focus on countries like Portugal, Spain or Italy. "Their interest rates would increase drastically, which would thwart the policies of ECB head Mario Draghi, who would like to prevent exactly that," says Jochen Felsenheimer, CEO of the investment firm Xaia.
Greece's departure would also be just as expensive for the remaining euro-zone member states as a debt haircut because Athens would hardly be in a position to fulfill its financial obligations. Its currency would be drastically devalued and its economy would be threatened with collapse.