I have a vivid discussion with my friends lately. They say that one day people will forget what cash is and they will start use card only. Then the era of the changed and innovated cryptocurrency world comes, and we will stop using money and switch on crypto coins only. They say it might take twenty or thirty years, maybe longer, but it is a sure thing to happen, they have no doubts about it. I am not so sure... well, people might give up using cash as it is not that convenient, but giving up money as whole? I really really doubt it, it seems so impossible for me. What do you think? Maybe we will start using something brand new, neither cash nor cards? What is the future of the cryptocurrency world, anyway? Will it die in fifty, sixty years or it is going to be a thing that will live forever? Let's dream for a while 
There have been different forms of money, gold and silver, fiat and crypto. In the future, there can be more. But the form is not that important because money is not determined by its form but by what it does and how it is used. If something physical like coins and banknotes or immaterial like digits in a computer or on the blockchain, is used as a universal means of exchange, it is money by almost every definition out there. Without money, it would be barter, highly ineffective and inconvenient.