Many commentators ask whether the Euro will survive the Ouzo Crisis. I dont think anyone really thinks that Greece can bring down the Euro. Paul Krugman put it well, reminding us that Greece is a sliver of the EU lands market size 

the real issue is contagion. If all the of PIIGS slip into crisis, the EU has to decide if the Union is worth the price (of a bailout of the PIIGS, which would have to be financed by the remaining EU countries). As Ben Franklin said of the colonies that formed the US (via Floyd Norris): “We must hang together, else we shall most assuredly hang separately.”