Bitcoins are dominant now ans everyone is accepting cryptocurrencies and thus.. many people are investing in it..with that many people investing in Bitcoins I don't think that there will be some country who forse this situation and go against public intrest.
In fact the countries which are non democratic can for sure do this but in case of democratic countries like japan ,India, USA.. I don't think they can do this because it will go against public intrest more or so the government is for the people by the people and from the people...thus every democratic government will look forward to make it legal by following certain norms offcourse.
We are all as bitcoin lovers expecting next time , bitcoin can be accepted and legally used all over the world. if this condition happens, it is really a very good news. Public interest in this adoption will be the first priority because it is very useful to all. What we need is a general regulation to control and monitor its operation to minimize or avoid negative impact of illegal use by criminal.