The headache for the exchanges should not be underestimated. There are several exchanges which put their BTC into storage and then create a mini-economy around them. If an exchange or other entity has their BTC lent out to 5 different people, it is fine, until all those people line up for their rights to the BTC-C. (There can be only one.) This is the Black Swan element of this announcement, and it remains to be seen how it will play out. This will be a very interesting next couple of weeks.