The simple answer is for Germany to leave the eurozone and reinstate the Deutsche mark. Doing so would be a benign act of rational self-interest by a sovereign nation. Most probably many current eurozone countries would leave, too. Without Germany to fund the budget deficits of the mostly southern members of the eurozone, the European Central Bank would shift its mechanism of plunder—the TARGET2 system—to the few remaining semiresponsible but much smaller nations. To avoid this fate, these more responsible nations would either adopt the DM themselves or reinstate their former local currencies and link them to the DM. This would leave the profligate nations of the former eurozone with no host to plunder. Reinstating their own currencies would probably be short lived, as no one would buy their bonds. The eurozone will collapse, leaving the only option, eventually—for all of Europe to become a DM zone, either adopting the DM themselves, as they adopted the euro decades ago, or through direct linkage of local currencies to the DM. A sound DM would force these former eurozone nations to adopt more responsible spending and regulatory regimes.
Reinstating the DM, a peaceful act by a sovereign country, would create a cascade of monetary reform throughout the world. Europe’s trading partners would find the cost of necessary imports rising in terms of their local currencies, forcing them to adopt fiscal and monetary responsibility. Gresham’s law—that overvalued money drives out undervalued money—would work in reverse in international finance, because there is nothing to force foreigners to settle trade accounts with the dollar. Governments certainly can use legal tender laws to force their citizens to use “bad” money within their borders, but they cannot force sovereign nations to do so for very long. Just as superior automobiles from Japan and South Korea forced US automakers to up their game, a strong DM will force the US to strengthen the dollar. If it does not, the world will abandon the dollar for international trade. All that is required for this process to begin is for Germany, a sovereign nation, to leave the eurozone and reinstate the Deutsche mark. No treaties are required. Germany needs no one’s permission to leave the euro zone. The sooner it does so, the better for itself and for the world.