The "legality" status of bitcoin only depends upon the mindset of the people and the government who is going to accept it . If government takes it as a threat to their fiat , it is never going to be termed as one of the official currency . There are outcomes of everything both positive and negative and with bitcoin i think there is a way to deal with every type of negative outcomes if it is handled with intelligence.
For some countries, it my illegal yet because they cannot yet accept the vision and the reason of cryptocurrency and that is to help promote the country and the world to become cashless and for it to help the world in having a worldwide innovation and that is thru the use of blockchain.