You win the prize for the most detailed response, caspar. Hands down.

Its smart of you to give an overview of different scenarios that could all result in a collapse. I myself believe that these other scenarios are a possibility, albeit less likely than the prospect of financial collapse (which I find to be inevitable).

If I had to assign a probability value to each of your scenarios, I would rate them like so.

War-related collapse: 10-15%. / War with Russia and China is more likely now than it was 4 years ago, but it probably won't escalate to the point where nuclear weapons are used. If there is any war at all, it will most likely be a conventional war between China and Taiwan. Defeat will result in a loss of prestige for America, but not an actual collapse.

Internal revolution: 5%. / A Far Right insurgency is more likely now than it was 4 years ago, but it still remains a long way off. Things will need to deteriorate alot more before the Far Right hits critical mass. People are still too comfortable, and have too much to lose.

Secession: 25-30%. / The prospect of states seceding from the Union becomes more and more likely with every year that passes, as the partisan divide in the U.S. becomes worse, and Washington blunders from one crisis to another. There are political obstacles to secession, but these may not prove to be insurmountable if the country continues on its reckless path to destruction. Eventually, some states will find it unbearable to remain tied to a decaying country, and the stage will be set for a breakup.

Mexicanization: 45-50%. This is the most likely out of all your scenarios, but it will require several decades before it yields a collapse. A financial crisis is likely to destroy the country before this process is complete.