I have read a lot about storing in bitcoin in cold storage in case of a fork
What would be the impact of keeping bitcoin in exchange accounts e.g. coinbase?
It would be better to store your bitcoins in cold wallet where you are fully in control of the private keys, if a fork really happens and the chain splits into two, you would still be able to spend your bitcoins on both chains. If you trust Coinbase that holds your bitcoins to handle this upcoming fork properly, you could still go ahead and store your bitcoins in their wallet, but I won't take the risk on that.