What happens to coins after Bitcoin Cash fork?

If you have 1 Bitcoin (BTC) before the hard fork, you will have 1 Bitcoin (BTC) and 1 Bitcoin Cash (BCC) after the hard fork.

Whether you can spend those BCC depends on who has control of your private keys.
If you currently keep your BTC on an exchange (Coinbase, GDAX, Poloniex, …) you need to check their policy w.r.t. the fork, since they control your private keys for you.

Coinbase for example has expressed that they will not interact with the BCC blockchain. This means that you will not be able to spend/sell your BCC until they either interact with the BCC blockchain or release your private keys to you.

If you keep your BTC in a paper wallet, you have control over your private keys, and 1 BTC will indeed result in 1 BTC and 1 BCC after the fork.

Today the value of 1 BTC is roughly $2700. BCC futures were trading for $350 last time I checked.

What the value of 1 BTC + 1 BCC will be after the fork is hard to predict and is subject to demand and supply on the markets.