I also think so, but every crypto has its own function. It's a lot to say that the fore only Bitcoins survive this because Bitcoin is the King of crypto. But another altcoin I think there is also like Ethereum that works as a virtual machine that can run a peer-to-peer smart contract with a cryptographic cryptocurrency ether (ETH).
As long as many projects are still growing and people want to invest in them, it is certain that many will continue to grow new altcoins. although maybe later altcoin that can not develop by itself will disappear from circulation. bitcoin and ethereum will clearly continue to appear, because both have complementary functions for the growth of the new altcoin. so I believe not only bitcoin and ethereum are still there.