The chance is very low to happen a significant inflation unless world war III or worldwide epidemic disease occur. Let's assume any of this happened. Will people likely to switch their fiat currency into bitcoin?
If that's what happened and people attempt to switch their fiat into bitcoin, there will be a chance of fiat currency become nothing of value.
PS- I don't want world war or epidemic disease at all. i am just thinking at what point bitcoin will take over the fiat currency system.
Anything can happen and untill it happens we cannot speculate about the situation. There are countries like Venezuela and Iran where people are investing heavily into Bitcoin but, you are talking about the whole world.
I feel if such a situation arises, people will primarily think about surviving than investing in Bitcoin.