I think the top 10 coins in marketcap will eventually survive in the future. They already exist before those hundreds of coins are made. They are popular and they are all legit coins that has an interesting project in the future.
I also agree with your opinion
Coins that enter in the top 10 will survive in the market.
Reason 10 coins are still used by many investors.
And it will still be used to invest because the price will continue to rise.
Being in the top 10 doesn't mean shit. Anyone can print up a bunch of coins. Look at IOTA. Had a $1.5B market cap or some such thing "unofficially" due to trading in slack (!!) before it even it bitfinex. Just goes to show market cap is meaningless. By extension "top 10" is meaningless.