The US $ will remain the world's reserve currency as long as it is the "petro-dollar" but the eventual destruction of the US currency will come from growing and unsustainable Federal debt. What is the magic "collapse" number? $18T? $20T, $22T? all depends now on where the refinance interest rates go on the debt. The 2% 10-year rate is all that has kept the currency viable for the past 4 years. Can the US maintain its lofty $15T+ GDP? is a real and honest question. Some of the components of current GDP are vapor compared to the tangible components of years past.