When the time comes and humanity can be independent through the technologies, we can say that there's a big possibility that someday, local fiat currency can change into Bitcoin and some digital currenciesand people will learn the importance of it or they will realize that the Bitcoin can provide the needs of the people.
Local currency means its given by your government so it will never get changed.
Bitcoin created by someone and not controlled by anyone,so anyone can use it as long as they wish to do,if everyone living in this world choose it might change fiat to crypto payment method.
Bitcoin gives freedom of using money,security while transacting,convenience,no hidden fee,no third part and transparency.