And interest rates will be fixed by the European Central Bank, after study of the likely reactions of the financial markets. And the EU has no bottomless central budget to smooth out such problems. At the European level, there is absolutely zero flexibility. The current tendency towards fiscal dumping will continue, as states compete ferociously to attract new capital, and keep the footloose investors they already have. In the USA, regional economic difficulties provoke widespread labour migration to more fortunate parts of the country.
European workers are much less likely to move from one country to another in search of work.
Language difficulties, and the national organisation of social security systems will continue to be brakes on such movement for the foreseeable future. In other words, there will be a harmonisation of social standards across Europe. But it will take the form of a downward spiral. The EU will clearly require a real government, as supranational as its new currency. This is the Achilles heel of the European Union.