It certainly would not be the cleanest process, but it may eventually be necessary. The imbalances are so extreme that it's hard to see how it won't eventually happen. Addressing the current economic problems hardly seems fair when countries are burdened with the euro. FT via CNBC:
To deal with what they argue are fundamental design flaws of the euro zone, they propose a "divorce settlement" under which some countries - ideally Portugal, Ireland, Italy, Greece and Spain - leave the union and a core group of countries remains in the euro.
The leavers should rebalance their economies away from growth led by debt to economies based on export and income-led growth while the core should rebalance towards domestic demand, they say.
They suggest currency realignment to achieve this, but admit that there would be disruptions.