First I think BCC needs to show they even have enough miner support to find any blocks to keep their chain alive. If they can't find blocks their fork will be dead before it even became alive. Exchanges can always decide to honor their customers their BCC coins if its chain survives and there is demand for it. Until then I don't see any reason why exchanges would need to give any attention at all to some phantom coin that doesn't exist and might never come to life.