Greek Exit Would Shake, but Most Likely Not Shatter, Eurozone(nytimes.com)
nytimes.com
Greek Exit Would Shake, but Most Likely Not Shatter, Eurozone
http://www.nytimes.com/2015/06/18/business/dealbook/greek-exit-would-shake-but-most-likely-not-shatter-eurozone.html
Once you set the precedent that a country can leave the Eurozone there will be a day that things get tight and then Spain will leave or Italy will leave -- somebody who is big enough to bring the whole thing down. It might take 10 years or 30 years but it will be inevitable.
Also Grexit will sour Europeans on the idea of any expansion so there will be no possibility of the Euro zone pushing further east which would be a great counter against Russian aggression.