The truth is, in the long run survival food is returning to the times of our Paleolithic ancestors, albeit with a supply of modern day tools, knowledge and techniques -- at least those that don't demand electricity or gasoline.
Many people probably don't want to hear this, but if civilization goes down entirely -- which is not likely but also not impossible -- we may have to rebuild from the ruins.
Freeze dried foods and other forms of emergency supply foods are great, and everybody should have #10 cans of freeze dried food on their shelves, along with cans of other foods and containers of water.
But let's face it, you can't buy enough emergency food bars to last you the rest of your life, in case civilization itself as we know it today collapses.
If sizable numbers of people survive the fall -- which they would, unless it's due to a massive environmental catastrophe, a pandemic or chemical or biological warfare -- then we'd still be unable to return to a hunter gathering way of life.

There aren't animals roaming in our woods. Although we're set up to have just a few percent of the population raising enough food to feed us all, that would be impossible once tractors, harvesters and combines run out of fuel.
We'll all have to go back to being small time farmers. We'd have to learn the skills of raising small animals -- goats, cattle, pigs, rabbits, ducks, geese and chickens. We'd need horses for transportation again and to pull plows.
We could grow wheat, corn and other grains. And plant large gardens again. And we'd have to learn how to can the excess from the garden to keep and enjoy through the winter.
We could also learn again how to forage through the woods. This was how our ancestors ate their carbohydrates for about two million years, before somebody learned how to grow grains and the agricultural revolution began.
Fortunately, we wouldn't have to start from scratch and take a chance with our lives everytime we tried a plant new to our small clan. We have a large supply of books by people who are keeping the art of foraging alive. People who remind us that weeds are simply plants we've forgotten how to use.
The grandaddy of them all was Euell Gibbons, who wrote Stalking the Wild Asparagus years ago. Amazon also carries a lot of others, some more valuable with color pictures as well. It's probably a good idea to get several of these books so you can cross-reference them until you have enough experience finding and cooking the plants that are in your local area.
The rest of the world, especially the developed world is more prepared for long term food disruptions. A favorite children's song in The Philippines is Bahay Kubo, about the many vegetables that grow in the yard of a small wooden hut in the country. My friends are looking forward to having their own piggery. And many people keep chickens.
It's not wise to bet our lives entirely on the existence of modern day food supply chains stretched across the globe. It's a good idea to hedge your eating investments by having survival food close at hand, just in case.
Next: survival foods -- because you can't store enough food now to last for the rest of your life.