Greece's government could leave the €, but the Greeks will not abandon their €.
In fact, many of the just moved their € from Greece's banks to germany's banks, to avoid any risk of bank's holidays and forced conversion to new drachmas.
If the Government just default on the debt or leave the €, it will need to pay every imports, good and service in € or $ or gold. In full and upfront.
The worst thing can happen to a government is just being forced to pay upfront and in cash for its spending and with someone else money.
They would be forced to tax as much as they like to spend. And, usually, this lead to peasants with pitchforks showing under the walls of the governments offices.
They would be forced to balance their budget. Ohhh the horror!!!! The HORROR!!!!
The default on the debt would cause an increase on the government debts of other countries. This is because they can not afford Greece to default, because this would cause a chain reaction of insolvency.
Italy, my country, is just on the brink of the default. 600+€ per capita added to the government debt will not help a lot. It would push the debt/gdp ratio near 140% in a moment.
Other smaller countries would be in similar situations. Their debt/GDP could be better, but their economy could not endure the increase of interest rate or just be unable to pay more.
Even Germany, their bank sector is vulnerable to defaults, because their banks are overextended (often a lot more than Italy's).
The QE is needed to backstop all of this injecting enough liquidity to prevent the other countries and their banks from popping like Christmas lights after the Greek government default.
What will happen is a large increase of currency controls. And this will benefit Bitcoin adoption.
With the exception of Argentina, currency controls doesn't bring any benefit to Bitcoin.
Anyway, Bitcoin is still experimental and probably most Greeks don't anything about that. Of course, it still remains as a great option in case of a bank run.
