The digital world was not made or discoverd to overshadowed the whole world or the physical world. But It was created to work side by side or hand in hand to make the world a better place not a competitive place.
I love this piece, people wrongly tend to think that the emergence of bitcoin is aimed at displacing fiat or other transactional means locally available to a sets of people, but its far from that. Bitcoin is designed to coexist with other forms of transactional mediums. It just serves major purposes which is an investment opportunity and giving you a total ownership of your funds.
Believe it or not, there are some basic routines which you cannot do or is pointless doing with bitcoin, for example buying a tin of milk or paying for short distance transportation which you can easily pay for with fiat in order to fast track your activities.
Bitcoin has its own purposes in our economic activities as well as fiat and surely, with the right information available to people, it's obvious they can coexist. Bitcoin and fiat also has a relationship in Bitcoin's high liquidity feature which enables the holder to convert it to fiat when necessary and you can also purchase bitcoin with fiat through P2P on exchanges. Fiat is not phasing out anytime soon, even as bitcoin adoption is increasing. So in all, both financial entities can coexist.