I don't think so that cash is going anywhere else, until the next fifty sixty years. Cash is now being the most basic form used by everyone, everyone may do not have a credit card or a bank account but they do have access to cash. Cash us the most basic form of currency. Any cryptocurrencies or any other advancement will not replace it that easily. Bitcoin is continously growing up and it's price are skyrocketting and still very less people know about it. I think cash will not be replaced.
Cash will not go extinct. Do you think how those who trade in traditional markets? Surely they will use cash and do not want to use a credit card or bank transfer. Traditional markets will surely be everywhere. Do not think that far and complicated, if we see people who sell food or soft drinks on the roadside, we will use cash to buy it, right? Therefore cash will not be lost. However, over time cryptocurrency and digital currencies will become more popular and more popular by many people and the world.