Someone who has worked extensively in the area of USSR break up and transition economies, he has some ideas. He looks at examples from previous break-ups and says Eurozone break up should be avoided at all costs:
One of the big questions of our time is whether the Economic and Monetary Union (EMU) will survive. Too often, analysts discuss a possible departure of one or several countries from the euro area as little more than a devaluation, but Åslund argues that any country’s exit from the euro area would be a far greater event with potentially odious consequences. A Greek exit would not be merely a devaluation for Greece but would unleash a domino effect of international bank runs and disrupt the EMU payments mechanism, which would lead to a serious, presumably mortal, disintegration of the EMU. It would inflict immense harm not only on Greece but also on other countries in the European Union and the world at large.
When a monetary union with huge uncleared balances is broken up, the international payments mechanism within the union breaks up, impeding all economic interaction. Åslund’s critical argument for a domino effect is that the EMU already has large uncleared interbank balances in its so-called Target2 system. Exit of any country is likely to break this centralized EMU payments mechanism. These rising uncleared balances are a serious concern because nobody can know how they will be treated if the EMU broke up. Any attempt to cap them would risk disruption of the EMU. These balances need to be resolved but in a fashion that safeguards the integrity of the EMU. However, this can hardly be done by anything less than fully securing the sustainability of the EMU. If the euro area does break up, Åslund says, the damage will vary greatly depending on the policies pursued. On the basis of prior dissolutions of currency zones, such as the ruble zone in 1992/1993, he suggests that an amicable, fast, and coordinated end of the EMU would minimize the harm.
It does not look easy at all. A really nice read covering a lot of ground on the break up of currency zones..