I've been saying for a solid 10+ years that the EU was going to fail. I figured back then it might take until 2020-2030 or so. Might just happen sooner than that.
Not only are they all (more or less) socialist countries, which alone would doom them to failure, but they also have, what, 2 dozen (give or take) different languages and major cultures. Here in the USA there might be 57 states (according to POTUS), and several significant cultural regions, but we have only 1 major language among the citizens, state boundaries don't connote millenia old ethnic and religious lines, and (except for a few years in the 1860's) one common currency since the ratification of the COTUS.
The EU has all the bad and none of the good. No surprise that even leftists like Krugman are recognizing that.