At same time, I don't think people would like to adopt decentralized cryptocurrencies as replacement for fiat currencies, because nobody wants to rely on volatile currencies in daily routine. The risks are too high, and people would live in a constant atmosphere of tension and anxiety due to the possibility of having all their funds losing 50% of its price overnight. As we know, it's something possible to happen in this market.
When it comes to currency or payment methods used in everyday life, what people care about is stability, convenience, low fees, and fast transaction processing. They really do not need a decentralized and highly volatile currency.
Therefore, I even think that even if the government legalized bitcoin as an alternative. Not many people will use bitcoin to replace fiat in their daily lives.
That is the thing, bitcoin has always been harder to "use" than fiat, and that is why there is no way that it can get adopted for usage that quickly. Online world got it first because in online world we do credit card information anyways, so it is not as easy as paying on the spot with a "beep" sound, you type everything in, at that point bitcoin can be used too, but even there, the waiting times are different, cards are instant, bitcoin takes time.
So if bitcoin ever needs to be something we use for daily spending, it needs to get faster and I mean much faster and also very cheap. Cards do take commissions, you pay for it, but at the same time, it's very tiny, so if you want bitcoin to be the same thing, you need to spend very little, like 10-20 cents at most, and be instant.
