One thing is if everyone is using crypto currency then everyone vould have access to the internet anywhere since it will be used for businesses. Next, if everyone is on crypto currency, I'm sure that countries will create their own coin so they can at least maintain a certain control on the market. Lastly, every one will have to have register so people will not use it for laundering.
If the countries convert to cryptocurrency we will enjoy cashless world and there would be no need for money change. One world and one currency and that would be definitely bitcoin. That world is the era of new generation. We would enjoy that time very much. People will feel ease while using their coins. Shopping and payment throughout the world will be easy than that of today.