We all heard that back it the Klinton gun ban days. Primers were supposed to be designed to self destruct. Powder was going to be made with taggants that would identify who bought it, and it wouldn't work after a designed date. Just bunk, but it caught everyone's attention.
On the other hand, even such a rumor of it coming to pass would make today's ammo shortage look like a party. Everyone would stockpile (hoard) the good ammo, drying up the source. Then we'd all buy the bad stuff to shoot currently. If I were a primer/powder/ammunition maker, it would be like a dream come true. Even the retailers would be increasing prices dramatically on the "good stuff".
Reality is much different. I've got ammo in my "collection" which is probably 100 years old, maybe more. I'm just afraid to shoot the stuff because of its value.
A hint: American made commercial ammo has an indefinate lifespan. It drives the gun banners crazy. They know its in everyones desk drawer, in their dressers, and in dad's workshop. And it so dependable its unbelievable.
So here's the next scare. We've got a bunch of new shooters coming along. Someone recently estimated 80% of the gun sales are to first time buyers (I say bunk, but what do I know.) They're going to equate their $2 a pop self defense ammo to milk or hamburger. We'll be inundated with questions about "how long will it be good?" Self serving folks will tell them "oh, at least a year from when you bought it", then adding "its not really safe to shoot after that, might blow up." Followed by "I have a buddy who specializes in disposal of that dangerous stuff, he'll safely dispose of any I bring him for free!"
