I am not sure what the end of the USA is supposed to mean. Civil war? It is possible. Civil unrest of some sort at least seems probable. But I think international conflict is the more pressing concern at the moment. American media is already peddling the perverse line that China is to blame for their economic woes because, wait for it, they saved too much.
That is fighting talk. Expect more vilification of China as the world economy falls off the cliff. History shows where bellicose rhetoric leads real conflict often follows.
It is not crackpot to expect things in the West may not in the future be as cosy as we have grown accustomed to over the past 60 years. There is no law of nature that says other countries can have failing economies, strife and unrest, but it can never happen here. It was not so long ago much of Europe was in ruins. I hope against hope we do not live to see that again.