I think for the future Digital currencies will change the monopoly of currency that is by the government of a country, just like the internet that changed the monopoly practice in the phone industry.
That means the decentralized system brought by bitcoin can bring about big changes. Change is deserved, for a better life. However, the existence of a central bank managed by the government also serves as an instrument of economic stability of the country, so I think bitcoin will be an alternative payment.