Sooner or later US Dollar will crash. When it happens most probably US government will face with issue of seperation. Most of the wealthiest states dont want to pay other poorer states debt. I think huge US debt will eventually will make US Dollar cash and this will lead to new countries and borders for USA.
Just my speculation:)
It will create chaos. The states would aim for independance, the world would need a new currency leader.
Altough the dollar is doom to crash (the debt is just too large), we have sufficient replacements; bitcoin, euro etc.