I think no more than 10 year MAX, Fiat currency is failing and digital must replace it. Ethereum , NEO etc can create the new economic system via Tokens, a token economy is near.
It will take us to more years to celebrate with the digital currency having a huge increase of value on it. 50 years would be much improvement happend. Many innovation of platform would developed and also with the blockchain.
If fiat currency will fall down but digital currency cannot replace it because fiat currency is our tradition,it is good to us if we use digital currency as a bitcoiners we can easily do any payments without any hassle,but the government will not accepting that fiat currency lost then exchange to digital currency because the government cannot control digital currency because of the blockchain technology,that is good to us as a bitcoiners that many years will come digital currency will improve and become much popular and many investors will come, and also people joining bitcoin will increase it's population and if it will happen bitcoin price increase very high and they will develop a new platform and blockchain tecnology that bitcoiners can get big benefits.