Its impossible to have one or two coins in crypto space because one or two coins can't solve all the problems we have in this world in every aspect of technology or others, if you want to keep a coin for a long time make sure the coin or token solves one or two problems in crypto space or the world, this type of coins don't die easily because they have real use cases, its simple as that
Your point is valid.
Ethereum has something that BTC never had and it took the already defined structure of BTC and improved upon it. (Smart contracts)
So did XMR which focused on privacy.
TBH, the top 50 coins in coinmarketcap are more than enough to solve most of the problems in the crypto space.
The problem comes when there are so many releases of new coins which are technically a fork of an already existing coin with nothing new in features, just that it has a new name or a new algorithm.