No doubt at the beginning, there will be turmoil and death.
But it will soon run out.
At least in terms of “wandering marauders” or whatever... the lifespan of a typical “wandering marauder” can be measured in weeks... or even days.
An organized group can destroy everything you have above ground in a matter of a few hours, sending you underground and at that point it’s over.
Marauders will not disappear; they will become an increasingly more dangerous problem. As the weak and stupid ones are killed off, the smart and strong will organize and gain power. Murder and theft will be their only source of supplies and they will become very adept at the black arts and many will be wearing badges.
History proves that evil men can be just as resourceful as the honest. Intelligence, leadership and charisma are not relegated to the good men. In a total TEOTWAWKI situation, the least obvious may rise to prominence and become strong leaders on either side.
People will band together out of necessity, or they will die alone. That doesn’t mean some sort of socialist or communist utopia, nor taking in random strangers into your home. It means like minded individuals creating a society built on mutual trust based on honest work, skills and an understanding of mutual defense.