Well Greece are tied to the Euro, though there has been speculation about cutting greece from it. But thats probably not going to happen...
I thought Greeks dealt in gold and silver coins. At least, that's what I learned from watching Hercules and Xena.
Well, we'll be leaving the Euro first (pretty soon), unless the Germans get to win that race.
And BTW, Hercules (your version) and Xena are Australians, not Greeks.
We have had black market economy and barter for thousands of years, under any conqueror. We will survive, no matter how hard it will be. It's only a pity that Bitcoin only exists for a couple of years. If it was a more established currency, as I expect it to be in a few years time, then any transition would be much easier.
Think that any weekend from now on can be default weekend for us. The government on a Friday night will declare a 3-day holiday for banks on Monday, Tuesday and Wednesday so that they have time to print new currency and change our Euros to devalued Drachmas. And freeze deposits at the same time.