This doesn't even include the so called 'shadow economy'.
I would expect panic in the shadow economy before there are defaults in traditional debt.
Since the two are not directly dependent, it's also possible that the opposite happens, only one collapses, or both collapse at the same time. The last option seems most likely to me, because debt bubbles tend to collapse if there is a general loss in confidence that often spreads extremely fast across all potentially weak financial constructs.
The exact estimate of China's payload doesn't matter. We all know that debts have risen far beyond the point of being manageable. It's not only China, it's almost the whole western hemisphere, including quite a few emerging market economies. The debt bomb may also be ignited by a rather small country (for example Greece) which might cause a sudden change in the mindset of investors around the globe.
ya.ya.yo!