Just look at denmark and the app MobilePay
It´s connected to your creditcard and you can pay anywhere with it, with your mobilephone. Even the homeless now have a sign with their code or phonenumber for mobilepay, as people almost never have coins anymore.
Yes I think we will see a huge portion of cash been digital.
Thats why I have started buying silver, and when I earn more money, I'll also have physical gold - It´s fun and interesting with digital cash, but I do fear something unforseen act.
Let´s just take the news these days: North Korea bombs Japan in a few years from now - China and north korea employs all their hackers to disprut the west, and a war begins.
If we are unlucky and most of our cash is in a centralized system, it might very well get frozen.
Well - I guess it's always good to putt your eggs in different baskets

Yeah denmark is one of the first country are developing their own country to become one of the first cashless country. Its not possible that cryptocurrency can replace money because of the innovation it can bring in our economy.