I think your statement is not entirely true, because Japan was actually the first country that accepted Bitcoin as a "Currency" and even if some other countries does not accept it as a legal tender, people still buy and sell Bitcoin without their permission. Examples of countries where this is happening is Zimbabwe / Yugoslavia / Venezuela / Hungary ...where they are struggling with hyperinflation.

Most of these people are forced to do this, because they need to protect their wealth against a failing Fiat currency. So yes... other countries will also do this, because more and more countries are struggling economically and hyperinflation is becoming more common now.