There are some dangers when one re-hypothecates something. Obviously, you design derivatives so that you can sell 2 copies of the same thing for the same price. It can be very addicting when it works. Just ask the Federal Reserve. These exchanges might have just been called to account. If there are 3 people with a claim to the same BTC, who gets the BTC-C?
Might be carnage over the next few weeks, and when the dust settles, the starting blocks set for the next Crypto race.