Western country are self suplient of food because we have engine and chemical industry, ones this goes down, shortage of food will be quick to come. In part of the world where labour is still mostly manual, it will be more resilient.

Also without bank, a lot of people will find themself without any properties and will likely get more violent. Again, in part of the world where people own real objects and not number in a computer in a datacenter, this won't happend.

I honestly think you have a way to negative outlook and heavily overestimate the US role in the world. But who knows