We don't need to speculate.

>Ratings Downgrade: The rating downgrade of the United States reflects the expected fiscal deterioration over the next three years, a high and growing general government debt burden, and the erosion of governance relative to 'AA' and 'AAA' rated peers over the last two decades that has manifested in repeated debt limit standoffs and last-minute resolutions.

It doesn't take an economist to take one look at statistics like this (among others) and think, "that doesn't look promising."

https://fred.stlouisfed.org/series/A091RC1Q027SBEA

Or, well, a lot of just general statistics around the debt once you consider what they literally mean.

https://www.usdebtclock.org