|September 26th, 2013
The world death rate is about 8 per 1000 people per year. (CIA Factbook) This is lower than you might expect because the population is increasing: average lifespan is not 125 years (1000/8). In a steady state the rate might be more like 14 per 1000 people, but let's stick with 8, describing our current world.
Most people die of diseases in a way that their bodies can be promptly recovered. If there are 50 pounds of edible meat on a body, then current deaths mean that every day human deaths could supply 0.001 pounds per living person. This is low-quality gamy meat because the average age of death among people is incredibly high for meat animals, so it might be equivalent to cheap $1/pound cuts of meat from conventional livestock. This means enacting worldwide cannibalism for humans would provide as much additional meat as spending one tenth of a cent per person on conventional low-end meat.
Not worth the social debate or the medical risk.