I was thinking economic collapse was the most difficult to pin down. There's economic warfare (attacks on the dollar, BDS, luring us into too many theaters, etc.) and cyber warfare, which could create many types of problems.
Agree debt's problematic and increasing the national debt has a certain momentum from Obama, but it has been reported that the national debt declined by $100 billion under Trump. I have not checked the primary source on that. Now it pops over $20 trillion. Didn't Obama close out his second term at close to that? What caused the debt to spurt over $20 trillion, I don't know. Maybe those savings went to get the military back on its feet, or go towards hurricane relief. Whatever. No time to research the debt.
But I see your point and am still for tar and feathering all those living who spent our SS surplus. Scoundrels!