"The Greek economy has been decimated by austerity. It is 20% smaller than it was 5 years ago. That cannot be allowed tp persist."
The reason its economy has shrunk so drastically is that it is saddled with a currency it cannot afford to deal in. Had it not adopted the euro the Greek economy would have floundered on the way it has done for years, the value of its currency would have decreased considerably and, by virtue of that fact, it would have remained competitive in what it does (80% of the Greek economy depends on the "service sector" and in Greece this is essentially tourism and shipping). As it is now, a cup of coffee in Athens is about the same price as a cup in Paris or London or Frankfurt. Two decades ago it would have been about a third or a quarter of the price.
The Greek crisis (and, to a lesser degree, the crises in the other "PIIGS" nations) has come about because the euro is a fundamentally flawed project and no amount of messing about printing sheets of the stuff will alter that. The current situation was precisely that which eminent economists warned against before the wretched currency was launched. It was launched as a political project to satisfy the vanity of the Euromaniacs.
The sooner politicians accept that the euro in its current form is unsustainable the better it will be for those suffering from having it inflicted upon them. It had no sound basis on which it was built, it will continue to stumble from one crisis to the next and the people paying the price for the biggest economic folly in modern times are the Greeks and those in the other troubled southern nations.