In my opinion. until any time the fiat currency will be needed and used throughout the world. technological advances in the financial sector will not affect the existence of fiat currencies. Digital currency is used to facilitate everyone in choosing transaction tools so that our work will be easier. and fiat currency is used for people who do not have a digital currency.
I think the answer is to ask yourself, are you still using fiat to buy something? I think most or even all bitcoin users must still rely on fiat to pay for their daily needs, you are right that technological developments will not change anything on fiat as the main currency
This seems to be a question that doesn't really need to be answered because everyone already knows and understands this question. This answer is all in yourself. No need to make an easy thing difficult.