What happens to the rest of the Eurozone if Greece leaves with out settling the debt?
Well, Greece would have to bring back the Drachma. Substantially devalued. Greece would be a shopper's and tourist paradise. They would have to get their economic house in order as the .gov will have very little to no money. Although there will be some morons (Yeah IMF, I'm looking at you) that would loan them money.
If Greece defaults, then Spain, Portugal, Ireland, and Italy will probably quickly follow suit. That would leave the Germans holding the bag, and being very unhappy. You won't like it when the Germans are unhappy.