It would be really difficult for something as popular as cryptocurrency to disappear within a few years, maybe in a few decades cryptocurrencies will disappear, but not in the coming years.
I think that just the same for several years cryptocurrency can safely disappear. It can even happen in just a couple of months if the market collapses. But I think that cryptocurrencies are promising and so far they are of great benefit to the whales, which means that as long as they need cryptocurrencies, they will not disappear.