Paper money is not going to last for more than 3-4 decades.Most of the paper money is going to be demonetized.I think that instead e-money is gonna be popular.Nevertheless paper money is a drag.
Why carry liquid cash,when u can easily do transaction over mobile,?
I think the reason it will not last forever not only because of its use is less practical but also because of the high inflation rate. that causes fiat continually loses value. I'm sure we will realize that the saving fiat in big quantities, is very harmful and risky, especially if we save the fiat aside usd.