No one can tell you what will happen in future. If Bitcoin truly vanish then cryptocurrency will exits? Where every altcoin depend upon bitcoin price. Bitcoin was the first invented and pioneer in crypto currency world. Everybody follow bitcoin price. Almost 10 years have been past with leading position. Bitcoin is not depending on one investor that one investor wont invest then bitcoin will be vanishing not like that it has huge number of investors so there is no chance to vanish of bitcoin.
It growing and become stronger everyday even if the price doesnt show it at times only because it has lots and lots of investors small and major investors creating huge demand for bitcoin. Crypto market, which we know cant be exist without bitcoin. Can you imagine any recipe without salt? like this Bitcoin is main cryptocurrency, bitcoin is the foundation of all cryptocurrency the first decentralized digital currency.