In the part of the world that there are no internet it is difficult for cash money to be extinct ,because you can only use this bitcoin when you are connected to the internet, and there will be enough signal that can cotter the need for the connectoin nd some transactions.
Not true. You can use hardware wallet or card with Bitcoin or other currency in it. How you pay with your credit card? You use internet while paying for a candy with your visa?
This is how is working now.
https://youtu.be/qbNG66nQdqAThis is temporary solution while fiats are still here
https://youtu.be/IjngOjwOrewThis is how it will work in near future
There was a video on youtube where Asian women buy coffee or something with a card that is loaded with crypto, but I couldn't find it and I was lazy to search it more.