This topic has been discussed few times already, if you hit the search button you'll find many topics similar or related to this.

Anyways to answer your question, no matter how popular bitcoin at the moment or in the future and it happen to be widely accepted already it cant replace fiat totally. Yes many people started to show interest to bitcoin especially in times of pandemic wherein many people stayed at home and find bitcoin (or crypto in general) as an alternative way to make money. But it doesnt mean bitcoin can dominate the world's economy and will become the primary currency that is recognized by everyone.

It can exist and work together with traditional currencies but it cant replace fiat completely.