That's ENTIRELY outside the scope of the study, and any arguments being presented here. NO ONE, at least that I've seen, has argued for EVERY person to carry a gun.
As to your scenario, it would have two probable impacts. First, it would weed out those not ready and willing to do murder or die with strong likelihood, and second, it would increase the violence and ferocity of the remaining criminal element who would then truly have nothing to lose. The end result of that, in a reasonable amount of time, would be that most serious criminals were dead (since they're outnumbered many tens of thousands to one).
That being said, I do not argue for absolute armament. Just for those that want it.