1) Balkanize the United States. Give each race a homeland, but keep some of the US like a Brazil so the halfies have a place to live; 2) Permanently cease ALL immigration; 3) (legally) Shoot to kill anyone crossing the border illegally; 4) Once Balkanized, give government incentives to white married couples to have kids. The more white they are, the more kids they have, and the higher the IQ of the parents, the more tax breaks and gibs they get (Poland and Hungary are doing this); 5) Make abortion for whites illegal. The punishment would be 10 years for the woman, 20 years for the man if he knows and doesn't report it, and the death penalty for the doctor; 6) Appoint a Culture Czar that monitors and stops anything anti-white in the msm, social media, etc. Anyone caught advertising an anti-white agenda will receive the death penalty; 7) Allow absolutely NO Jews in the ethnostate

Wouldn't a better solution involve making sure the overall quality of life rises enough so that the demographics slow down all across the world, rather than just in the west?

No. The science says that demographics itself defines the overall quality of life.