Hypothetically, if the US economy collapses, the whole world is going down with them, and those that survive the socio-economic collapse (i.e. the first order producers with a defensible military), will be free to do as they please assuming the nuclear powers don't say, "fuck it" and blow everyone up as they lose control. The "If I can't have it no one else can", unthinkable insanity which all human beings are prone to given sufficient stress.

Every end can be a beginning depending on how flexible your thinking is. The unfortunate part is, most people today have had evolutionary selective pressures towards narrow and brittle thinking. So a great many people will be left out in the cold along with everything that normally occurs in a Malthusian reversion with the caveats that Catton is likely more correct than Malthus in that regard.

New Zealand

As the other commentor notes, if other economies are sufficiently dedollarized, the damage will be limited, and global dedollarization has already begun.

For a while. Then everyone dedollarizes and fights over which one should be the premier currency of trade.

Why do you say that?