I am an American paying off a French mortgage denominated in euros? Obviously I have been enjoying the recent increase in dollar value, but what would happen if France decided to withdraw from the euro? How are values of existing loans and other investments re-negotiated? Is there anything I should be doing to prepare for the possibility?
I would expect France’s central bank would have to decide upon an exchange rate between the Euro and their new(old) currency. They might offer separate rates for cash/bank accounts vs. debts.
But they would be forced to establish their own sovereign currency pretty much immediately, and would attempt to set the rate at something that would not destroy too much of France’s wealth held in Euros…
I get very, very, very rich. And then I have lots more currencies to trade 
Lots more currencies, but likley a trigger to another global recession as everyone takes their funds out of stock markets.