[SA-R]

To keep stable and strong common currency for countries which are not on the same development level like it is situation now in Euro-zone, it is not cheap at all, actually it cost huge amount of the money, so it is stupidity and luxury of the Euro-zone countries to leave open door forever to some countries which are members of the EU but they don't want to join Euro-zone.

If we have common currency, than it is not financially healthy system to have common market without protection to those countries which are not in same currency and etc zone.

Solution:
Simple question with time deadline, "my way or highway"! Least one thing is sure, Paris, Frankfurt and Berlin will need extra offices a lot.