Convinced that money can be used to trick those who use it to exchange real wealth, Morici and many others think a devalued drachma will make Greek products cheaper such that the country can export its way out of its depressed state.
Once the new currency is in place, mortgages to Greek banks would likely be repaid in drachma, while repayments of mortgages to foreign banks may have to be renegotiated.
What is really being said here is that if Greece leaves then Greece can, quite legally, simply state that all debts contracted under Greek law can now be settled in the New Drachma and the fact that this is worth less than the old euros makes no difference.
The consequences almost certainly would include the inability of Greek corporates to service their euro- and dollar-denominated debt if the drachma is readopted as an operating currency.
However, if it were to reintroduce the drachma, the new currency would quickly become worthless, while the private Greek economy went underground and continued to do business in euros.