The possible/likely scenarios -
Bring Out Your Dead - UBS Quantifies Costs Of Euro Break Up, Warns Of Collapse Of Banking System And Civil War | ZeroHedge
...not exactly comfortable to read or contemplate
"
the historical parallels are unappealing. Past instances of monetary union break-ups have tended to produce one of two results. Either there was a more authoritarian government response to contain or repress the social disorder (a scenario that tended to require a change from democratic to authoritarian or military government), or alternatively, the social disorder worked with existing fault lines in society to divide the country, spilling over into civil war. These are not inevitable conclusions, but indicate that monetary union break-up is not something that can be treated as a casual issue of exchange rate policy"