There's no reason why the Euro zone should explode because of one smallish country leaving the club.
Then, it's very different from Cyprus, there aren't many wealthy people with big assets in Greek banks.
Most if not all Euro zone countries have financial problems.
Greece and Portugal already caused trouble to Euro zone, Greece leaving might start a trust crisis or something
When the Spaniards and the Portuguese will see what happens if Greece leaves the Euro, they'll shut their mouth. There won't be any domino effect. Greece will just collapse if it leaves the Euro. Thousands of Greeks will emigrate to other countries, and there will be people starving among those who stay, I mean people dying from hunger, if the country leaves the Euro. Imagine that all civil servants, all policemen, will no longer receive a salary, and that the people who have money in the bank will not be able to withdraw it. Nobody wants that, unless those who don't understand the situation.
The governments can't betray their voters by getting buttfucked by the troika. They either betray their voters and get off the euro, or stay in the euro under merkel's dictatorship generating more and more protests.
It's a fucked up situation no matter what.