Our federal deficit interest rate is like 15% of government expenditures.
The dollar being the reserve currency which leads to demand for the dollar keeps the dollar from deflating.
But as people no longer demand the dollar because they don't want to support a imperialistic government what happens?
The US would no longer be able to export the cost of its spending on other countries which is the so called 'extraordinary privilege' of running the world's reserve currency and the US population would feel the consequences of its out of control spending.
Which is to say, that is a fairly traditional way of how empires go the way of the dodo. First losing their financial dominance, which loses them their international power, which then causes internal rupture.