I talked to a guy who was an engineer for a company that produced metal lids for glass jars and bottles. He told me that recently his company had changed materials for the plastic/rubber lining of the jar lids to a material that was BPA free. He said that many food can manufacturers were doing the same thing. He also said that the new material would not last nearly as long as the old material and that food in jars with metal lids and in cans probably would not have near the shelf life in the future.
Hormell has stated that their canned goods, though they have a listed expiration date, will last indefinitely if the cans are properly stored. This includes SPAM.
How long will canned good last?
YMMV, but this site as articles/info regarding shelf life, how to read expiration dates, etc.
StillTasty: Your Ultimate Shelf Life Guide - Save Money, Eat Better, Help The Environment
A friend of our owns Grabill Country Meats, and he says that as long as the can is intact, it will be good. That could be 20 or 30 years, or more.
I think the biggest concern is not if it will be safely edible but how much nutrition is lost over the time past the expiration date. There are some fancy calculations available online that help you figure this formula out as best as you can.
When I buy my canned goods I always ensure there are no dents in the can. Microscopic cracks can form in the metal and allow air and bacteria in.
another good rule is to plan on losing 1/3 of your stock to contamination. Not that it WILL happen but just in case, you've already planned ahead and stocked extra.
im a firm believer in eating what you store. FIFO (first in first out). I mark all of my goods with a permanent marker with the month/year it entered my stock. Easy to keep track of.
also look for the dates on items at the store. They also use FIFO and stock newer dated product at the back. I shop from the back but always check dates.