No, entirely not. What would happen overnight is that the currency would plummet against all other currencies into Deuschemark territory, at which point there is no import/export possible with that currency. This is not a simple problem to get oneself out of, dear random internet commenter, which is why you don't want to get into it in the first place. The spread between the official rate and the black market rate already reflects a shred of the drop that would occur if the currency floats.