Just want to add this:
Most likely BCC will have some values. And this value would probably dilute the value of BTC. So please make your effort to allow access to the two coins possible for your Coinbase customers in the near future. I bought BTC as a long term investment, so if you can make it happened in the near future, I am fine with it — as long as it happened. I just do not want to see my hard earned money going into the toilet.
As long as you still have our BTC private keys, the BCC will not disappear from your exchange; we still own it.