The future era is the era of digital money like Bitcoin, Litecoin Altcoin etc. In this Morden society every generation people wants to walk with new cashless methods. No one wants to carry a bundle of paper money with them while going for shopping. It make feel you unsafe and unnecessarily filled you pocket space. In many countries there government motivate their people to ise more and more digital currency. For those above reason i think  digital currency will replace paper money.