As we all know, the Khmer Rouge managed to kill one of the highest proportions of a country's own population ever in just four years, with average estimates of population loss in the 20% range. Assuming that they don't get invaded and that they don't substantially reform for several decades, when would the population losses plateau? Presumably there is a point when even Pol Pot would realize that he's rendering his country defenseless with massive purges. Also, at some point, all the "New People" and other suspect groups will have been killed off, and, either they'll have to start killing loyal rural Khmers in large numbers (which they were perfectly capable of) to the point of total collapse, or just ease off on the genocide. At what point would they run out of non-vital victims, and how many survivors would there be on that day?