I know that tomato, corn, beans and some of the cole crop seeds will store for really long time if done right, but some things like onions and leeks and lettuces will start losing germination rates after about 2 years, and you have to plant them to grow out at least every other year.
I've also had old squash seeds last well over 10 years in a nice dry, dark container, so I'd bet they would do well packed like your beans were.
Beans are funny critters, they tend to be quite stable even the hybrids, at least the ones that I have grown in the past. They pollinate themselves mainly before their bloom even opens... But I have switched to all heirloom and open pollinated veggies as they are easier to keep seed from and usually taste much better than hybrids, but in a SHTF world I would grow and eat what ever I could plant.
One suggestion on seeds, store and save mainly what you enjoy eating and those that are good nutrition like the corn, beans, tomatoes and squash... sure I like my fancy veggies like lettuces and such, but if I had to survive on my garden I think some of the less nutritious stuff might not get as much room!
Another seed that people overlook is true potato seed- you know when the potato plants make the tiny little green/purple looking baby tomato things on the top- those seeds while not really breeding true (you might get bigger or smaller or even a bit different than what you started with)will still be potatoes and you could always grow out more each year.