One problem with your scenario: No one has anywhere near enough ammo to fight a protracted war. Most everyone has a couple hundred rounds max. Maybe sounds like a lot but in a conflict you could go through that in a day. Then what? Hand to hand? I don't think most people have the stomach for this, especially the ones who say they do, because unless you have been in combat and had bullets whiz past you and at you, you have NO idea what you would do in that situation. A fair amount of people will run like the wind after soiling themselves.

Which begs a question, what if this whole thing is to get people to burn through their ammo so they can be taken out after by some as yet unknown force that will come in to mop ALL of us up left or right, when the smoke clears from the initial conflict? What I would do, is prep as you said, but DONT get into any conflict except in absolute self defense and conserve your resources as much as possible. We DONT know what is coming.