Cryptocurrencies, in turn, do not have such a clear status of use as a blockchain. Of course, we can say that they are independent units for calculations, but they are independent because the blockchain makes them so. No one will say for sure how long the fashion for cryptocurrency will last, because in a decentralized way it is quite possible to send Fiat if agreed with the government.
Cryptocurrencies do not have very strong prospects and their fate depends on how governments perceive their status. We can expect both the extinction of this movement in favor of several strong coins, and the growth of cryptocurrencies that will be created by many services as loyalty systems.