It's not easy to kill cash because still many people don't know and understand cryptocurrency and they will keep using Cash.
Whats your view about this
good imaginination... but cash is money in the physical form of currency, such as banknotes and coins. Cash has now become a very small part of the money supply. Its remaining role is to provide a form of currency storage and payment for those who do not wish to take part in other systems., and make small payments conveniently and promptly, though this latter role is being replaced more and more frequently by electronic payment systems, then born virtual money and virtual currency.
Virtual currency can be used as an alternative to money . In that case, digital currency represents electronic money (e-money).
As such, bitcoin is a digital currency but also a type of virtual currency. Bitcoin and its alternatives are based on cryptographic algorithms, so these kinds of virtual currencies are also called cryptocurrencies. Cash is increasing in circulation day by day.. Maybe for future all transaction adopted with cryptocurrency payment but seems impossible replaced a cash became larger and a standard coin for international payment. only due alternative payment seems possible.