While I can't speak for an ideal subsistence farmer might act, out here in rural USA it would be very unusual for anyone growing crops to not store food and gro

While I can't speak for an ideal subsistence farmer might act, out here in rural USA it would be very unusual for anyone growing crops to not store food and grow more than they strictly need. Canning, freezing and other forms of long term food storage are vital, otherwise you have 50lbs of okra for a month and 0lbd the rest of the year. Once you have those processes down, it's not hard at all to scale up even 50% and can a few more tomatoes. There is all sorts of informal barter for veggies and meats here, and the excess gets sold at farmers markets. The urban folks do have slight end of chain distribution advantages. The imported food is consolidated at the grocery store or wherever. The price will be high, but you can pick new sources as they are available. The city folks will be reliant on diesel for production transportation of the food. While the rural folks rely on diesel for production of food and for buying the rest of the goods they need.