As the EU continues to fracture, this power vacuum could create a 21st-century equivalent of the late Holy Roman Empire: a rambling, multiethnic configuration that was an empire in name but not in fact, until its final dissolution in 1806.
This means that there is still no alternative to American leadership in Europe. For the U.S., a Europe that continues to fracture internally and to dissolve externally into the fluid geography of Northern Africa and Eurasia would constitute the greatest foreign-policy disaster since World War II. The success of the EU over many decades was a product of American power, stemming from the victory over Nazi Germany. For all its imperfections, the EU, even more than NATO, has been the institutional embodiment of a postwar Europe that is free, united and prosperous.
Source: Europe’s New Medieval Map – WSJ