That's a difficult question, if bitcoin would stop to exist today than probably ETH will take its place as the new leading crypto currency. The crypto boom has already happened and there is no way people would go back to a world before cryptos. The demand is still strong for an independent currency that is not influenced by central banks.
If it so happened that bitcoin would stop exist, then I'm not sure that ETH will be able to take the place of bitcoin and I don't know how cryptocurrency will be trustworthy about after thet. All such bitcoins are number one and if something happens to it, then everything will change, if it happend with the strongest coin, then what can be expected from the rest of the coins...