Many have been predicting for the better part of a decade that a Comex default was inevitable and in many cases imminent.
While a default is certainly possible, its not likely because Comex is not a place where people come to buy and sell silver and gold. Rather it's a place to buy and sell silver and gold long and short contracts.
Comex is a place where people sell silver and gold they don't have to people who don't want to buy it.
Here is the latest Comex short position data: