They make some good points and there's some good "food for thought". I think the real question is how much food a family can feasibly store and the sheer costs involved. If you're an "MRE-Head", plan on mortgaging your home to afford a pallet-load. On the other end of the spectrum are the folks with 2-cases in the cellar sitting next to a few jugs of Poland Springs. These people are doomed, unless they've got some serious hunter-killer genes.
For my family, it's all about balance. We buy what we can, when we can. We also have our own garden, can our own veggies and jams and live in an area where we can forage, (short of a local nuclear disaster). I hope North Korea never Nukes Berkshire County...
I think much depends on exactly how and what shit hits what fan. I can tell you, that there's no way we could hunker down in the cellar for a whole year on what we have - not close. Eventually, we would have to go out and forage. From where I sit however, there's a year's supply of food right in the woods - from the gray squirrels on the feeders, to the cambium of the trees, to the moss on the rocks and the worms underneath it, right down to the skunk under the back porch. Hell, everything tastes good with garlic powder and tobasco...
If necessary, I'm certain the SOCOM could easily dispatch a milk cow up the road if need be....
I think the best prep is that of the brain. If I spent all my paychecks on MRE's and pouches of freeze-dried eggs and crates of ammo, I suppose I could plan for a disaster that may, (or may not) come. However, reality is that I have bills to pay, mouths to feed and dog food to buy. I also like to get out and enjoy life a little. I have enough realistically to keep us fed for awhile and enough grip on reality that I will likely have to use my brain to survive after that......