Read this good article on the difficulties of maintaining the Eurozone. Here are some of the big problems:
France and Germany, which have the biggest economies of the 12 countries that use the euro, are breaking the strict budget rules governing the currency by running huge public-spending deficits. Growth continues to sputter in the euro zone, while the United States is showing initial signs of recovery. Unemployment has risen to 12.5 million. And the near-record-high value of the currency is hurting competitiveness by dampening exports. Last week voters in Sweden overwhelmingly rejected adopting the euro in favor of keeping their national currency, the krona.