This will not happen, in my opinion. The US dollar has the world's largest and most powerful military backing it. Bitcoin has nothing but the belief of the community in a decentralized platform. Bitcoin may grow and become huge, but I do not see it replacing the dollar.
We all know what happened when middle east oil czars try to sell their oil in a different currency. "Regime change" occurs in their countries.
This is spot on
Any attempt to change the US power structure will be met with force, happens every time and this is why they put so much in to military.
In 2015, the US will have a declared military and defense budget of $601 billion, which is more than the next 7 highest spending countries combined
Also look at the trillions spent on the middle eastern wars alone, #1 military means far more than national debt to the US.
In saying that, the US have done some intentional things over the last 30 years to spread wealth over the globe, allowing most of it's work to be off shored has killed it's middle class and made others powerful, they are the biggest pusher of globalism and one of the steps for true globalism is a global currency, bitcoin/blockchain may just be this, the top Bitcoin holders are all American and Satoshi could be too, or even an American agency
http://time.com/money/5002207/richest-people-with-bitcoin/All of those people are American.