And why do you think everyone will sell their BCC?, in fact I believe at most only 10k will be sold, rest will keep it as an hedge ,
Both poloniex and coinbase have stated they have not decided if they will allow buying or trading of BCH
So far all we know is they will allow you to withdraw to a wallet I dont know how this will affect things since a lot of people just keep their coins in coinbase instead of a paper/haedware or other wallet
The coinbase people can just transfer their BCC to another exchange wallet. I don't think coinbase will block a transfer if the address you transfer to is an exchange wallet or your own personal wallet.
They say "by" Jan 1st... it could be before that.