While the scenario of a lone homeowner holding out against all odds is a real fighting persons fantasy that is mainly what it is. It will take a very short time and there will be marauding packs of various guerilla groups and their campfollowers. The homeowners with the most vigorous defenses will be seen as probable good pickings to harass until they wear out and are mopped up, the hiders will be shucked out of their hideouts like peas out of pods and disposed of. Their arsenals and food caches will be stolen and used to continue on.
The only real defense is in numbers and a system of communication and alliance so that when the s hits the fan a rapid pulling together of resources and people can take place. It would be the wisest thing to base this kind of activity on being Americans pulling together and helping other Americans no matter their race, creed, religion, and all of that. We still have the skeleton of the old Civil Defense system in place and it should be brought back up to truly being useful.
Now doesn't that make more sense than some kind of total chaos everybody for themselves horrifying pileup?