It's not the currency; money is just a medium of exchange. It's the foolish behavior of Greece, et al. which has caused the crisis. They all overspent and overborrowed.
There is no magical reason why the Euro works just fine in northern Europe but not in the South. The author is suggesting that the only way out of the crisis is for those countries to rob their citizens through inflation.
Of course, that's quite stylish these days.
Au contraire. The Greeks and others were given massive incentives for their overspending and overborrowing. As most people know, when incentives are given most people will respond to them.
The answer is not to expect people tp be nobly self-denying and ignore the incentives, it is to avoid providing the incentives in the first place.
Multiple currencies act as a kind of free-market check and balance. Nobody would have lent the Greeks all this money if they were going to be paid back in drachma, subject to devaluation if too much was printed. Being paid back in euros backed by Germany, no problem!