There are two different ideas about how cryptocurrencies look in a few years.
The first group of Bitcoin maximalists says that there will be the only Bitcoin and anything else is useless, worthless.
The second group says that technology is every day more and more advanced and old blockchains will be replaced by a new one.
Bitcoin and Ethereum doesn't seem to be mutually exclusive and I don't even think that at this point they are necessarily a competition to each other. Bitcoin is the leading store of value solution and Ethereum is doing an entirely different thing with building a platform for DApps, DeFi etc. I don't think Ethereum will replace Bitcoin but I also don't see any crypto replacing Ethereum at what they're doing in the near future.