Gresham's Law and Zombie Banks

From TC at NYT:

ALL of the ways forward look ugly but, sooner or later, some variation of at least one of them is likely. Unfortunately, they all share the property of lowering European bank values, whipsawing currencies, hurting business confidence and possibly ending the European Union as an effective institution for collective decisions. That’s all because the euro, in retrospect, appears to have been a misguided attempt to equalize the values for some very unequal assets, namely the bank deposits of strong countries and those of weak countries.

ATSRTWT