I don't really agree with this analysis. I expect that the 2008 oil shock was the Gavrilo Princip of the current financial crisis. The amount of debt was certainly at unsustainable levels, but it seems possible that things could have continued for another year or so before some other trigger, such as higher interest rates, brought the whole thing crashing down.
Saving you the google search: Gavrilo Princip was the assasin of Franz Ferdinand, which started the chain of events that lead to WWI. http://en.wikipedia.org/wiki/Gavrilo_Princip