Difficulties like what? There has never been anything as important to bitcoin before then to step over the threshhold to get the legal framework and instututional funding. Everything before this has been just fun and games.
That the (then-current) powers that be try to stifle innovation is as old as the Earth. And yes, sometimes they succeed. Name one.
1. No country with a right mind will replace fiat for a currency that is controlled and owned by anonymous individuals, who have no responsibility over that currency. And who are also in high probability former criminals, when you consider the history of bitcoin.
If any country was truly independent, it would have adopted Bitcoin already, mainly because of the fact that it would make them insanely rich. It is like if Norway was asked, "do you want to have all this oil for free, we can give it to Scotland also?" Of course they take it.
2. There are no mechanics in bitcoin that enable it to offer price stability. And please don't try to insult my intelligence by telling that wider adoptation will create the stability. As long as bitcoin is very attractive to speculative play, then there will always be strong volatility.
If you quote prices and wages in something, no matter what, they are stable in that. (Duh.)
USD or anything else does not have price stability either - it can fluctuate against other fiat currencies, gold, commodities, real estate, goods - tens of % per year. In the long term, gold has better served as a provider of price stability. During the gold standard, this was natural (see the comment with "Duh"), but even afterwards, prices denominated in gold have fluctuated less than prices in USD. This is mainly because of the persistent inflation of USD, of course, but that is the only way to keep a fiat system inflated due to the requirement to pay interest to 100% of the money base.
As long as Bitcoin grows, it will have a high volatility. When it matures and becomes a global quote currency, the volatility against other things settles to a level at most comparable to today's USD.
(Adam Smith's / Antal Fekete's) Real Bills are a vehicle that can accommodate the need of self-liquidating credit in an economy.
3. If an country would use BTC as legal tender, that is both attractive to speculative play and distributed by an unregulated market system, then it would be extremely easy to cordinate economic attacks by hostile countries.
There is mainly one global enemy to the sovereignty of countries, and you are likely employed by that. Of course the country has to realize the prospect of economic warfare, but really everything is better than the current fiat slavery. I would probably use a currency basket method in internal contracts (employment contract wage
BTC0.01 + $5 per hour) and many other things. It is quite novel, and therefore interesting.
Fiat isn't just a piece of paper that is printed. The main difficulty for sustaining a quality currency is keeping price stability, and it isn't something that is created by itself. It is created by taking into account the available resources or foreign currencies and by regulating the flow of money according to that information. When the regulation is done right, then prices keep stable and it is possible to make plans with the support of that currency. Bitcoin has fixed supply and therefor it's not able to regulate it's flow to offer price stability. It's all about attracting investors with it's high possibility of deflation.
Sweet talk does not cover the fact that the record of post-1971 USD as a "stable currency" is abysmal and horrific; it has utterly destroyed the nation that in the 1960s was the powerhouse of the world, and now is a shell, producing nothing, and living off of sucking dry the rest of the world. The inhabitants of the USA are impoverished by innumerable means and are now totally indebted by the booms and busts made possible by this irredeemable "stable" dollar. I could go on but let's leave it here.
When you want to talk about BTC replacing fiat, then open your own business and start to use BTC with converting it to fiat only quarterly and try to earn profit with this instability. You can only start dreaming of BTC replacing fiat after services like BitPay would become useless, but I can't how that could happen with fixed supply.
Why would I ever need to convert it to fiat? Owner of Localbitcoins never has more than $100, all his business and personal finances have been in bitcoins for years. My business is ill-suited for your experiment because I trade between fiat-BTC-gold-silver. But one of my companies seem to never have converted its income to fiat nor used it. (Link in sig)
Right now, when someone is asking me "Why couldn't we just use BTC as fiat", then it sounds the same to me as some kid would ask me on why couldn't he just pay with his monopoly money. There are complexities involved that bitcoin is just not able to handle.
I give you the benefit of doubt that you meant it sincerely. Nevertheless, you are wrong. I mean, I see that we are moving to the direction that makes it possible in the coming years, and technology always wins.