The latest update of BCH market is that it trades at $690.38.
How dd you come up with this price? In reality it's much lower, less than a half of it.
https://coinmarketcap.com/currencies/bitcoin-cash/ $270-$280 since yesterday. It's even lower than I expected. I thought it to stabilize around 0.15 BTC, but people keep dumping

It's not going to surpass BTC, don't count on it. Not enough interest and mining power. It will go up though in the long run.
For sure it will still have some value after this but OP's prediction of it taking over bitcoin, would not come true. Also, I expect more dump to come after poloniex distributed BC to their users who have or had balance before august 1. I'm sure they will dump as well because no matter what the price, they will still get 100% profit from it since it is free.