O cerne da questão

This is a political more than an economic issue. It is possible for a currency union to survive sovereign defaults. The question is, rather, whether members believe the arrangement remains beneficial. The difficulty for surplus countries is that they must finance those in deficit, accept external adjustment or push the eurozone into external surplus. The difficulty for deficit countries is that the cost of leaving the eurozone is to face debt crises. If those have happened already, the costs will seem smaller. If they think they have replaced currency crises with credit crises, which do not even restore competitiveness and growth, they may see the union as a bad deal. Political glue could melt. Such calamities do happen. It is now up to the members to see that they do no

Martin Wolf, Financial Times