In the current situation I think paper money will not disappear. There are many things to consider and in reality it's not easy to be used this online currency. Because others can't adopt easily this online currency and paper money is still the original use even in the future.
As of now Japan is the center of Bitcoin, but they still use paper money coz not everyone can afford to have Bitcoin. There are country which are not adopting crypto and there are certain places that there is no internet connection. In this scenario paper money will not disappear.