I don't agree with your statement. Most of the people will use their country currency they don't beleive in virtual currency we know that its a good cryptocurrency but still offline people do not trust on these they all want safer money with less fluctuation on the other hand we know that Bitcoin has big potential to move up. I see in coming 10-20 years its not possible anyway but can't predict the future. A normal person never took the risk to use highly fluctuated currency & In my opinion real money can't be disappear.