There are many country are adoption Bitcoin as a digital currency in their market.And some countries will focus on it and anytime they will be reached a positive decision about legalize Bitcoin.After adopting more countries, Then more retailers will accept Bitcoin.
with many countries starting to accept Bitcoins, they will start enforcing its use if they their benefit in this regard. For example, if a country decides heavily in Bitcoins and invest large amounts in it, then they will force the local market and retailers to transact through Bitcoins. They may offer discounts to retailers by persuading them to use Bitcoins. In this way, Bitcoin can spread like an air.