I don't even know where to begin here. Looks like a group of posters either didn't understand the tittle or skipped it.
It clearly says 'FANTASY' :
the faculty or activity of imagining impossible or improbable things.
Stop discussing why it can't/won't happen, but rather what will happen with Bitcoin if they do.
There are solutions for all the economic problems that could be affected by adopting bitcoin. The real problem is that you need a very educated, young, modern and flexible society for such a scenario.
I can’t see any nation that would be able to adopt bitcoin as their official currency (for now), but particularly watching at Greece:
There are other solutions but they aren't achievable in this corrupt system. However, with Bitcoin the story is different. Certain groups of people will lose their control, something that should have been done a long time ago. I should be the owner of my money, and the banks should not be able to touch it. If you remember the situation with Cyprus, you would know. They just take a cut of your hard earned money, one didn't even have a say in it. This might happen to Greece as well.
In the scenario mentioned in the title: I think that the price and adoption (outside of Greece) would rise exponentially. Greeks would increase the price enough for others to join, and so the ride would begin.