I seriously do not recommend this idea you have. There are already multiple huge services that new exchanges cannot compete with (Xapo, Coinbase, etc). 
Sorry to burst your bubble.
Hmm are that the big exchanges? I thought they real big exchanges are Bittrex, Poloniex and Cryptsy. Sorry to burst your bubble.AFAIK is xapo a wallet and not an exchange.
Greetz,
FruitsBasket
bittrex,poloniex and cryptsy are altcoin exchanges and used by peoples for trading altcoins only while other, their bitcoin usd exchnage volume is too low