From Coinbase:
...
Over the last several days, weve examined all of the relevant issues and have decided to work on adding support for bitcoin cash for Coinbase customers. We made this decision based on factors such as the security of the network, customer demand, trading volumes, and regulatory considerations.
We are planning to have support for bitcoin cash by January 1, 2018, assuming no additional risks emerge during that time.
Once supported, customers will be able to withdraw bitcoin cash. We'll make a determination at a later date about adding trading support. In the meantime, customer bitcoin cash will remain safely stored on Coinbase.
Anyway it will build some trust. Just hope both BTC and BCH can hold or up from the current level
From Tech Crunch:
But heres the thing its currently really hard to sell bitcoin cash. While some exchanges have added the new currency for trading, liquidity is super low, which is why some say the price is being artificially inflated. Because most exchanges arent accepting deposits yet, the only bitcoin cash available to trade is currency that was credited by exchanges after the fork. Users holding bitcoin cash outside of exchanges, or in exchanges that dont support trading, are stuck waiting.
So the moral of the story is that theres probably a ton of bitcoin cash waiting to be sold, as soon as people can transfer it. Thats because theres not a whole lot of incentive to keep the coins, especially when people think it is overvalued and want to quickly cash out.
https://techcrunch.com/2017/08/02/wtf-is-bitcoin-cash-and-is-it-worth-anything/