As free market libertarians, shouldn't we just say that the market will sort this out? It will create a market demand for mechanisms that allow exchanges to demonstrate their solvency.
Stop using such logic, this is no time to be thinking that way! People are here hurt, crying and pleading for government/fed/law enforcement/lawyers/etc. to save their money; once that happens I'm sure they'll be fine and back on track saying the market will sort stuff out (as long as it benefits them that is).