For instance, one may think about off-ramps from exchanges. If getting close to the date of a fork it becomes evident that the event will create a major market disruption, even a three days lead time will not be enough to run to safety because most wire transfers will take longer than that. There are private banking services that hold the equivalent to nostro-and-vostro accounts with exchanges to facilitate the operation of arbitrage traders, and those should benefit from this situation (and that can be measured using the flows approach). But even those fiat banking platforms have limitations in the amount of business that they can handle when a catastrophic, fat-tailed event occurs. And if some are located in jurisdictions that happen to have banking holidays days before the fork, that stresses the system even more.