S&P expects a sharp drop in Greek GDP if the country leaves the Eurozone with GDP to fall by 20% over the course of four years. Greek banks and the payment system will not be able to function without the financial support of the ECB. The national currency, to which Greece will have to switch back to, will lose a lot of value against the euro, leading to an explosion Greek debt denominated in euros.
Our view is not so bad. A restructuring of debt would allow Greece to save a lot on future interest. A new currency would be weak, making Greek assets cheap and in which case more investors would be attracted to the country. Tourism to Greece will become better value for money and therefore more popular. And a sovereign monetary policy for the country would allow the Greeks to solve their budget deficit problem. The main banks could be nationalized. Of course, in the short-term, the Greek economy awaits a drop. However, after an exit from the Eurozone and a devaluation of the drachma, the country will be able to quickly return to growth. This is, of course, if we measure economic growth using macroeconomic indicators and not dollars and euro.