User blog:Fegaxeyl/No US superpower - but how?

I remember a while ago there was an idea for a timeline where the Soviet Union collapsed around the end of WWII and the ramifications of that. That didn't go very far.

But here, I'm wondering what it would be like if the United States collapsed between 1945-50, or otherwise ceased to be a major world power. Obviously this would mean no Marshall Aid, so Western Europe would be unlike to resurge quickly. The USSR would be left as the sole superpower.

But how would this happen? Are there any ways for the US to collapse after the end of World War 2? The only solutions I can really think of are some kind of revolt by black soldiers from the war, an economic disaster, or a new Spanish Flu. Obviously though, the POD could be from pre-World War 2; the Great Depression having some other effect, and so forth.

Anyone have any ideas, or up for debate on the results of a US collapse?