The Greek economy is in trouble; the population is agitating, trying to avoid financial pain, but their system allowed much unpaid excess - it's likely they'll default.
Too bad for them.
But this will not cause the euro to collapse. Once the Greeks are slapped with the worst their creditors can dish out, the euro will stabilize -- strong as ever.
The Wall Street Journal and other American propaganda rags denigrate the euro, and have done so throughout its history. But they would - the euro is top competitor to the almighty US dollar, and by talking down the euro, they build up their own currency.