I think that the end of the cryptocurrency can come anytime, but the blockchain will live for a very long time. This is a very necessary technology, in these realities, it has a practical application and many corporations are already implementing it.
If you mean a particular crypto currency then you are right probably, but there are dozens of projects which will be successful in the future, and the probability of them disappearing is very low. There is a big difference between the probable end of
some crypto and the end of
all crypto. The former is very likely to happen while the latter will hardly happen ever. As you said it yourself, blockchain technology is a very useful one, and I can only add that it is useful to such a degree that it's hard to imagine the future world without it.