I think this is based on the use case of the coin involved. If the use case isn’t really moving or being noticed, the project will definitely die off because something more attractive and popular and probably with even better use case has come. If we look at Ethereum, we can see why it is never coming down or going to hell like the FTT, etc. Ethereum is a power house, so many platforms are built on it so many tokens are on the same blockchain, yet the token is needed for transaction fee. That’s just more than enough use case. Tells a lot about how long Ethereum Blockchain as a whole can stay.
ethereum undoubtedly has the most used utility right now, the transaction fee alone already speaks a lot about the real utility that ethereum is having. even there are so many L1 blockchain that inherit their underlying system from EVM with a little of modification and succeeds gathering millions of dollars investment easily.
Ethereum is truly revolutionizing with its feature honestly the smart contract is just too good.
this is the case with altcoin that have real utility, its time less, doesn't matter at what time it is maybe few decades into the future we would still see ethereum getting valued high because the upgrade keeps rolling out and the demands will definitely persists.