I would only expect smaller countries to adopt bitcoin as legal tender, not the big boys whose economy's are vast and lots of influence to other countries like US, China and Russia and any country in EU knowing how centralized their monetary system and policy there. Expect next country will be from Latin America, Africa or Asia, except in Middle East knowing how their official currencies are tied on oils.
Even in smaller countries that is very unlikely. Honestly, I wonder what benefits using bitcoin as legal currency would bring to their economy? Many people say that El Salvador's economy has improved thanks to bitcoin, since they legalized bitcoin, is that true? Does anyone know what El Salvador's economic strengths are? How can we ensure their economy is improved with bitcoin? As far as I know, their strengths are tourism and agricultural exports, so what does this have to do with bitcoin? If bitcoin really impacts and helps them improve their economy, then why do they still use USD as their official currency instead of eliminating it?
Bitcoin volatility will bring more risks than benefits to any country's economy, we need to face the problem and accept that fact.
Yes, its just my opinion for smaller countries, but that depends on many economic factors.
Benefits of making bitcoin as legal tender is still a big debate between those skeptical and those who support to this move. Economic improvements are considered in different ways like many crypto projects moved and have office based there due this legality thus more jobs equals more taxes. Also, tourism has major effect knowing its their (El Salvador) forte, many crypto enthusiast go/went there to at least experience of a place where bitcoin is fully accepted.
Abolishing the use of USD is a suicide move in any country where imports and exports prices are based on this currency or any currency to be precise, so it's reasonable that they will still use it. Of course it depends on where to exports/imports, say China and Russia mostly preferred to use their own currency when accepting imports/exports but most of these countries use USD.
Well, it's true that bitcoin volatility matters, once it drops the value of their reserve will be in danger, that's why it's too risky move.
Now, just based on idealogy, a country being bullish on bitcoin will lift up others to do so and demands will go rise then price will go up. Of course, someone will dump it as in free market.
For the record, as of the current price, assuming El salvador didn't sold any fraction of their holdings either in private since there's no official announcement made in public, their bitcoin holding is in profit, knowing they buy something in the last few years in price range of $40k and $60k.