"At least 4 billion "useless eaters" shall be eliminated by the year 2050 by means of limited wars, organized epidemics of fatal rapid-acting diseases and starvation. Energy, food and water shall be kept at subsistence levels for the non-elite, start-ing with the White populations of Western Europe and North America and then spreading to other races. The population of Canada, Western Europe and the United States will be decimated more rapidly than on other continents, until the world's population reaches a manageable level of 1 billion, of which 500 million will consist of Chinese and Japanese races, selected because they are people who have been regimented for centuries and who are accustomed to obeying authority without question." pg106
Disagreement between the elites (about how many "manageable population" is)?
The problem is both in the sheer numbers, and in the way 'modern' people live completely out of harmony and sustainability with our biome. Food needs to stop coming from stores, and mainly be produced by those who wish to eat. This one simple adjustment would shake out much of the deadwood, but the entirety of what we call 'modern' needs to go.
The biggest challenge would be self-regulating our own numbers, and avoiding the boom/bust cycle found in so many mammal populations.