I concur with your reversal of order of collapse in America.
As do I - and I think that the cultural collapse lead to the others. Of course, this thing is VERY complex. Why the cultural collapse? Was it a lack of religion? People too busy working to give their kids a moral education? The lack of grandparents living with the kids & g'kids, resulting in a loss of historical and moral memory? Many, many causes are involved. Someday, someone will do a 30-part miniseries on it.
In the meantime, the conclusion that our fiat currency will become worthless is probably not wrong (i.e. it is correct). Buying the physical commodities that one needs to live (extra food of the non-perishable or long-lived type, key spare parts, etc.) or to preserve value (precious metals, tools, appliances, etc.) will be the smart thing to do.