The idea that the euro has "failed" is dangerously naive. The euro is doing exactly what its progenitor - and the wealthy 1%-ers who adopted it - predicted and planned for it to do.
"It's very hard to fire workers in Europe," [Mundell] complained. His answer: the euro. The euro would really do its work when crises hit, Mundell explained. Removing a government's control over currency would prevent nasty little elected officials from using Keynesian monetary and fiscal juice to pull a nation out of recession. "It puts monetary policy out of the reach of politicians," he said. "[And] without fiscal policy, the only way nations can keep jobs is by the competitive reduction of rules on business."
As another Nobelist, Paul Krugman, notes, the creation of the eurozone violated the basic economic rule known as "optimum currency area". This was a rule devised by Bob Mundell.