Bitcoin is not scalable enough to replace fiat.
But it can be an additional asset, a secondary currency.
Bitcoin is more scalable then normal currency which in present form requires centralised points to regulate its worth. A free market solution will always outweigh a proprietary system, I guess I refer to crypto overall there as innovation could mean bitcoin is surpassed. The problem FIAT has it depends on a monopoly to exist, its a token for taxes.