The direct power is with miners. But Bitpay, Memo, Coinbase etc will determine which fork stays. The users will stay with the coin they can use. My point, dont be too arrogant.
I tought that too but the fact that bitcoin unlimited and bitcoin xt never won over the miners on btc chain gives me pause. The miners didnt move because the businesses didnt.
Maybe, anyway I think the more clients the better. It should be extremely easy for businesses and miners to switch clients. Hopefully this will help that.