I can't help but think that the population rationale you describe is based on antiquated logic. Yuval Harari has already pointed it out. If you interpolate current technological developments, most humans will be rendered useless in the future. The more you have of them the greater liability you have on your hands.

As we can all see today, India is a perfect example of this social time bomb. Add to that that in the post-fossil-fuel era, little of today's operational logic remains standing. Food, production and distribution will all change dramatically. The importance of the local availability of material resources and efficient distribution networks will increase. Add to the need for high levels of concentrated capital investments and extreme levels of effective social organisation.

So forget Africa. Forget India, South and Central America and the Arab countries. The US is internally too divided and vulnerable to southern influx (unless it merges with Mexico and Central America) and Canada is not rich enough. Australia is not intelligent enough, nor organised. Europe's and Russia's only chance is if they merge into a Eurasian power block and get rid of their totally misplaced moral superiority complex (but the EU is currently run by Trans-Atlantic stooges, so that will not happen soon. Nor will the US nor Chinese let that happen.) So that leaves China (which has the money, organisation and effective population policy and has the political will and scientific know-how to use genetic enhancement). And perhaps the countries surrounding the South China Sea (if they learn how to cooperate, bundle their resources and enhance the quality of their populations- or are absorbed into a greater China.