Well it's difficult to say.
While some people foresee Bitcoin as having the potential to become the primary global currency - I currently don’t.
And please don’t misunderstand: I’m very bullish on Bitcoin, and (disclaimer) hold some Bitcoin - so I’ve certainly got nothing against it, and I anticipate that it may be a profitable investment over the mid (a few years) to long (quite a few years) term.
That said - as pretty much everyone has noticed, Bitcoin is still very volatile, in terms of price swings.
That’s not bad, or unusual, for an entirely new type of asset in an entirely new type of asset class, with small but rapidly growing secondary trading markets.
At the same time, though, it’s essentially the opposite of what people and nations understandably look for in a “primary monetary standard” - which, for some decades now, has been the U.S. dollar.
That’s because the U.S. dollar is exceptionally stable, at least in comparison to other currencies - and especially for an unbacked fiat currency.
Somewhat ironically, so-called stablecoins are the most stable cryptocurrencies - because their value is directly pegged to major fiat currencies, such as the U.S. dollar, the Euro, the Yen, and so on.
Which gives you an idea of how volatile cryptocurrency markets in general, and Bitcoin in particular, currently are.
I’d guess it will be at least a few years before that changes enough for any cryptocurrency or token to be reasonably utilized as an actual competitor to fiat (national) currencies.
My sense of it, though, is that blockchain and tokenization technology - which allows for the creation of cryptocurrencies and other digital assets, will cause the nature of monetary standards to move in the opposite direction.
Meaning, rather than roughly 200 currencies in the world (presuming one per sovereign nation) — I anticipate that we’ll have thousands - because, with blockchain technology, it’s easy to have thousands of currencies, track them, securely exchange them, and keep tracking of ongoing market exchange rates, 24/7/365.
As to the “why” this would be the case, the use case and benefits boil down to many communities quite possibly benefiting from having their own currency or token.
“Smart Cities” will have streaming, metered payments for various technologies and related services, and putting them on the blockchain allows the residents of that city to be able to get relevant discounts, and for autonomous cars and buildings to do the same; for residents to pay related taxes in a streaming, continuous manner - so there won’t be big, hard to pay chunks (i.e. property taxes) of outflow - but, rather, a continuous stream of tiny amounts - much easier to bear. Residents could get various discounts for paying with their metro area’s currency, thus keeping the money “in-economy” and “in-community”, thus benefiting everyone in it.
And non-geographical communities of all types would be able to offer commensurate benefits in various ways, by tokenizing.
And so, just as delivery of documents and packages basically outgrew government postal service - and the only reason “regular mail” can’t be delivered by, say, UPS or Fedex - is because the law says so - with chances being very high that it won’t say so much longer.
Just as there’s no clear reason for the government to “own” mail delivery (or rather, that there’s no longer a reason; what made sense in 1789 doesn’t necessarily make sense in 2019) - there’s no reason for government to own the creation and legitimizing of money, either.
Ultimately, it’s all about liquidity — everyone makes more money when money flows more freely —- including governments.
And so, before too many more years pass, governments will likely see the wisdom of getting out of the way of “currency freedom”, and allowing any blockchain-secure token to be considered legal tender - legitimate currency.
Most governments did that fairly early on with things like ecommerce and email - because they saw that getting out of the way ultimately benefited government, too.
I could be wrong, but I foresee that same dynamic happening in the fairly near future with cryptocurrencies.
It may take a bit longer, because of the government’s attachment to control, where money is concerned —- but, just as with everything from electronic stock trading in the early 1970s, to ecommerce coming online in a major way around the turn of the 21st century, to high-frequency stock trading not long after —- the macroeconomic and direct financial benefits to government were so strong, and the related use cases so compelling, that the applicable government authorities readily agreed.
Once that happens with cryptocurrency, Bitcoin will undoubtedly have its niche - but I’m guessing that it will also be ignored in favor of other digital assets and tokens that are custom designed for various local, regional, national, global and non-geographic use cases.