It is my contention that the main driver of the crisis was located in the financial sector, particularly banks which intermediated large capital flows towards the periphery, creating imbalances that became unsustainable when a sudden stop occurred following the international crisis and the abrupt revision of price of risk that it entailed.
The second question is useful to consider whether the construction of monetary union would have been sufficient to ensure a gradual correction of vulnerabilities and avoid a crisis, if a major international shock had not occurred. One can speculate that, left alone, the euro area may have been able to gradually overcome its own vulnerabilities through a process of interregional rebalancing.