Governments wouldn't make BTC illegal simply because they can see that their people benefits from this type of currency aswell. They knew how convenient this can be. Battling each other will just make things chaotic. Some countries are already using Bitcoin as their currency and they don't regret a thing or two because this just makes their life uncomplicated. In reality few countries are thinking already how will they adapt to this. An example of a country that is using this as their way of making the money flow is Japan. They made it as a legal currency, numbers have surged since their government passed a new law last year, making bitcoin as a legal form of currency. Bitcoin isn't a danger and won't be a danger for banks out there. Bitcoin will make things revolutionary.