Digital currencies are too young to be thought of as a failure. I think the future is full of countries accepting cryptos and to the last time when the last man accept and use crypto in their daily transaction. Crypto has come to stay and it is backed by a system that is trusted. I perceive mass adoption of crypto in the next 2 years. Everyone will see the positive side of crypto soon.
I am agree, its too early saying digital currency fail, because what in digital world, digital currency will be needed. Cryptocurrency at 10years old and the development very fast and the market value rising. Mass adoption will happen and the future of digital or crypto currency is more bright