World's "reserve currency" has changed throughout history
The United Kingdom's pound sterling was the primary reserve currency of much of the world in the 19th century and first half of the 20th century.
I imagine the current reserve, the US dollar, will also change someday. When it does, look out; the debt will certainly matter.
PS: I view the USA like the guy who falls off a 25 story building. As he passes each floor, he says, "so far, so good" (but MOI has no idea what floor we just passed.... BEEP BEEP).