You are right on many of your points but the land we are talking about is the swamp lands of northern Ontario where my family were born and raised off of. My parents were born there in the wilderness and they learned to live on their own without much else. I was taught how to live there myself and I can be comfortable doing that again because I know how.
You are right about food scarcity. The land I'm talking about will only be sustainable to a small group of people that know how to live and follow the seasonal cycle of this part of the world. Extreme cold in the winter and clouds of biting insects in the summer. Food will be cyclical so one has to know how to prepare for every period of the year and how, when, where animals, fish and birds will be available and how to prepare and store them for times of shortages. My parents do have stories of being out there and having to live through famine when animals just disappeared from one reason or another.
All this doesn't guarantee my survival in this scenario ... it just means my chances would be higher than most other people.