It will continue to spread as long as people care about their privacy. Bitcoin does not have to be a dominant currency. If countries regulate Bitcoin usage, there is no point in using Bitcoin anymore.
Bitcoin now a days is going to be more usable coin, and if some countries use it as their currency would not be a bad choice, the countries which obtain bitcoin mostly considers the best countries and economically these are strong countries. Bitcoin is far better to store and to make it more and more for our young generation, and also with having these we should give our young generation more information about the trading, so in the future they can gain a lot of profit from these bitcoins. The mostly countries are considered successful because they care for their young generation future. And I can say than young generation is the back bone of a country.