Outside of El Salvador, I don't think any developed country will accept bitcoin as legal tender, it's almost unlikely.
El Salvador is still a developing country.
It has to go from small nations, developing ones to middle and large nations.
So far there are only two countries where Bitcoin is legal tender and they are all small nations.
Legal tender countries.
El Salvador and Central African Republic.
Small countries with small economic sizes are more flexible with their national policy changes than big countries but I am very bullish that the mass adoption trend will continue.