if it gets to that will severely shift power and conflict capabilities. Your thoughts on explosives is wrong skilled chemist can make chemicals from junk, scrap and bio waste.
With governments storing trillions of rounds of ammo unlikely in our present generation to run out before not enough people left to fight. More like ww4 will be sticks and stones as Einstein said.
As for learning fighting with alternates it is good workout and less than lethal is required to enforce group standards.
I know many who practice unarmed vs armed, given choice all would rather be armed it is last resort.
Most in such a harsh reality would not have time and calories to train, it would go back to a type of feudal system.
Blades bats and other improvised weapons are in use in countries with gun restriction. Not like these guys train to use them they just do, it’s not like the movies close combat with non firearms is uniquely savage and a single person will not survive a mob jo matter how trained as you cant fight for more than 5 min full out. Look at mma best guys winded in a 5 min round I doubt many can equal thier physical prowess and training.
https://www.devonlive.com/news/uk-world-news/co-op-stops-selling-kitchen-2725688
Most modern martial arts have become sports no longer traing for kill but points. So few actual combat arts and even less available for civilians. Finding a good teacher is near impossibe. Can’t find this in strip mall.