Money changed its shape through the history. As from non-monetary exchange to the need of having money. Fast forward to our current banknotes which are in my opinion slowly dying with bitcoin taking over. Many discussions are being held if bitcoin can be the primary currency in the world. Let's assume it can be. Everything has an end so what do you think will come after bitcoin? What will money look like hundreds of years from now? I predict its gonna be digital of course but I'm interested if its going to be a cryptocurrency or something else.
Right now making any assumption about a new form of currency doesn't make much sense. I doubt many could have predicted blockchain and cryptos. Moreover, cryptocurrencies are in there initial phase. They are not even mainstream yet and talking about currency after it is baseless as of now. But yes, when supercomputers become a reality, we will need a better replacement to crytocurrency.