I think if they ate cheap beef and battery farmed chicken they's die even sooner than if they stayed on SAD.
Eating primal is not cheap. I pay dearly for grass-fed meats and dairy. I had to increase my food budget by $50/week. Thankfully I'm earning more now than I did this time last year, but if our family suffered an economic setback, I'm not sure what I would do.
They only way this could be sustainable on a global level is if every single person eating and breathing thought first about their environment and the neighbors BEFORE they thought about themselves. There would be no room for greed or dominance if the whole world went primal, truly primal, according to the "Blueprint." Because then everyone would be healthy and happy. Imagine a whole world of healthy, happy people. You may not need to lock your door.