Adoption has been happening already as cryptocurrency is slowly gaining popularity over the years now. Total adoption, on the other hand, is yet to take place. For it to be able to reach that level of ubiquity, the government and its regulations should be involved. Why? trust issues. I don't think the rest of the world would be willing to invest in something that is extremely volatile. If the government and banks give their full support, there is a mighty good chance for this event to happen.
The moment government adopt the blockchain technology, I am sure they will start thinking of how to regulate it, I know that many of us believe that cryptocurrency cannot be regulated, they might not be able to regulate it directly but a system will still be created that will make it a partial centralized system.
With time, adoption rate will gradually grow to its peak, just that it will take time and not be as fast as government influence on it, but I know that sooner or later, they will also buy into the idea and see the reason to rely on cryptocurrency just like I heard that some countries are already doing so, top countries like USA who would always want to stay on top as the Giant of the world will not watch smaller countries take advantage of the TC before them.