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.
No, that is not the only basis why paper money will not last, it's just a value and even if it's subject for inflation what you are getting if you are working will also increase or being adjusted by the government. It's the government that created paper money, hence they will do everything to keep its value and people will still use it. Government has taken in charge of this world and whatever they want will be followed, I do not even consider bitcoin as a competitor of fiat as it's way behind in terms of value and popularity.