Cryptocurrency replacing fiat isn't that easy, to experience a complete usage of cryptocurrency same as the fiat it needs a large scale adoption. Compared to the previous year what we experienced by this year is a massive fall, but adoption has been taking place in a gradual manner. With this I believe, in future can experience cryptocurrency usage same as fiat but replacement won't happen.
well, many things need to be considered in this matter. although cryptocurrency shows a rapid development, but I don't think it can ever replace fiat, even if it can, it will be very difficult. we know that crypto prices are very unstable. although fiat is also unstable, however, it happens for a long time, while crypto occurs in a short time.