In my opinion it's very unlikely that BitcoinCash(BCH) will kick out Bitcoin(BTC) out of the first spot. Theoretically possible, but very unlikely. Even so, if BitcoinCash(BCH) were to beat Bitcoin(BTC), I'm sure it wouldn't happen after the Segwit2x fork. It would take lots of lots of years of convincing people to use BitcoinCash(BCH).
I agree. Past all of the forks AND all of the other altcoins available, Bitcoin has the largest market cap and has been the coin that is the most supported across those who use crypto and also those who don't. Currently, tech companies are bringing bitcoin into their systems for payment processing, and this will only continue to make Bitcoin's worth much more than the different altcoins that are available right now.