This is interesting, seems Coinbase will give access to both chains after SegWit2x fork!

"Customers with bitcoin balances stored on Coinbase at the time of the fork will have access to bitcoin on both blockchains. There is no action required from customers and bitcoin can be securely stored on Coinbase before, during, and after the fork."

Source: https://blog.coinbase.com/update-on-the-bitcoin-segwit2x-hard-fork-69426f14bc85