Yes I think that bitcoin will replace FIAT all over the world, but it's code should be improved again and again.
Bitcoin can not replace fiat no matter how we try.
Fiat is to a large degree already digital, much of the fiat are just numbers in a computer, which are in only a few servers controlled by only a handful of people.
Currencies have been under heavy inflation in the past, for e.x. there are banknotes of 250 000 000 Zimbabwean dollars.
The more the money is printing, the more close to that situation we will get. Consider this theoretical example:
Average cost of bread
year cost ($)
1930 0.09
1940 0.10
1950 0.12
1960 0.22
1970 0.25
1980 0.50
1990 0.70
2010 2.00
2020 4.00
2030 8.00
2040 16.00
2050 32.00
2060 64.00
2070 128.00
At this point, will people still use fiat?
IIRC, the Zimbabwean people started to use USD instead of the Zimbabwean dollars during the hyperinflation period.
So if the value of USD starts to go crazy, people will likely just switch to use other fiat (EUR, GBP, CNY, JPY, ...)