>> EU united their currency from several individual ones and they are doing great...more countries are thinking about adopting Euro which rivals US dollars now
I am not sure EU is doing great when Switzerland has voted to limit freedom of movement of other EU nations into the country. There are few that will think EU is doing fine at this point based on the currency unification. Without EURO, Greece would have avoided its problems. They will simply devalue their currency. But with none, no instrument to play.