Bitcoin is also legal in the United States
And in a couple of them it can even be rightfully and legitimately considered legal tender, though at a local level only (and as a commodity at a federal level). But that's not my point. Simply put, you can't ban what you can't prevent. Bitcoin is like gravity in this respect. Technically, you can pass a law or proclaim a court ruling that would ban gravity for good but will such an order have any effect on it?
Good point. The distributed nature of Bitcoin makes it difficult to enforce laws that would prevent the complete usage of Bitcoin within a specific region. Of course, anyone caught using Bitcoin in a country where it's illegal, will face serious consequences. But, "banning" the usage of Bitcoin, won't prevent it from being used secretly or from being maintained by other people worldwide. Considering how governments have their different views one from another, they cannot reach an agreement in many things.
I believe the same thing will happen with Bitcoin, where there will be some countries in favor of it, while there will be others against it. It's very unlikely that a global government crackdown would happen anytime soon, because of said reasons. However, if this happens, then it will be completely disastrous for Bitcoin and other cryptocurrencies.
Nonetheless, we shouldn't worry about this, since many governments nowadays are seeing Bitcoin and other crypto as a great tool for taxation. With this, Bitcoin and other cryptocurrencies will be legal tender for a very long time. Just my thoughts