I think Ethereum will retain its core developer/userbase as they transition to ETH 2.0, but the worldwide crypto market is still nascent with lots of room to grow. This is where blockchains like AVAX, NEAR, DOT, Solana, Algorand, Telos, WAX, HIVE etc. will get their userbase from - people who have yet to even get involved, and prefer cheap, fast, and easy to use.
Also consider that Bitcoin and Ethereum are the major "blue chip" cryptos, so a lot of blind capital has been thrown at them by wealthy individuals who know nothing about crypto.