The interesting question is not whether Greece leaves the Euro, or the Euro leaves Greece, but how many of the opposition will be arrested before the next election.
The victory of the hard left was made possible by arresting the hard right and forbidding them from campaigning.
Which had the effect of discouraging anyone from disagreeing with the hard left
Greek politics is already dominated by police intimidation and the direct use of state power to punish dissent. Election of a hard left party is likely to increase the use of police intimidation and the direct use of state power to punish dissent.
The left, which is to say the state, talks about the side of history. History tells us that if you use state power to suppress your opponents on the right, by and by your opponents on the left will use state power to suppress you.