I think you are incorrect on your analysis.
Not your analysis that government will be powerless to do anything... your analysis that says nothing gets done.
We've a history of getting on just fine without a feral government.
They don't do anything anyway, except act as parasites. Everyday people in flyover country make everything go.
/johnny
IMO it depends on where you are and what happens. Pretty much anywhere on the eastern half of the US has more people then the land can support. Anywhere with a population of gimmees (regardless of race) is in trouble. The one positive is those people will probably sit on their butts waiting for the govt to save them until its too late.
The catch is the first week will be dangerous unless you’re in an area where the feral ones get organized under something like Islam. Here in Florida the thieves are out before the wind dies down.