And in the next 20 years bitcoin will become the single standard means of transaction in the world beyond the role of the US dollar, yuan, yen, euro and others.
That's pretty much unlikely to happen, Fiat currencies could be at it's low atm, with devaluation, inflation/hyperinflation etc and also a struggling economy due to the pandemic to make things worst, but unfortunately, it's somewhat not possible for Bitcoin to become the only (single) means of carrying out transactions; newcomers to Bitcoin are always pretty much enthusiastic to suggest that, but the reality is that the use of Fiat currencies wouldn't diminish. Bitcoin is currency of control, freedom etc, that makes it slightly different from our regular Fiat currencies, and imo, BTC works pretty fine with Fiat currencies around (when they coexist), even when Bitcoin becomes mainstream, it still would be insufficient to be the "single standard means of transaction".
This phenomenon will be absorbed by the majority of countries in the world to then take strategic steps through the regulation of their monetary authorities in accommodating the existence of bitcoin. This was created because bitcoin was able to guarantee equal trust without intervention so that it was considered fairer and safer.
The thing is, the government do not want any currency they can't control, manipulate and print as much as they want, when they want it, and having said that, Government involvement or accomodation of Bitcoin ultimately results in regulations, which then erode the control and freedom it's users are in the network for.
Unfortunately, there is still no reason to rejoice. States, governments and their structural organizations in general are not yet going to use bitcoin in their calculations, and this is hardly worth counting on in the near future. If there are such cases, then they can be considered isolated.
Bitcoin and other decentralized cryptocurrencies are not suitable for states due to their "no-man's" nature, high price volatility and uncontrollability. There is no doubt that they will issue their digitized central bank currencies using blockchain technology. In addition, the higher the price of bitcoin rises, the more states will have a desire to regulate the circulation of cryptocurrency more stringently.