Migrants from other developed countries don't want to come here anymore. They now move between Europe, Canada, Australia etc.

Actually, it's the US system that treats everyone the same, no matter the origin. The points system which you claim to know but don't assign different scores to lets say someone from Japan than someone from Nigeria.

This liberal talking point of migrants from Africa being better educated is also silly, considering that African colleges barely rank in the top 500 globally. Regardless, trump was probably talking about the millions here in the last 2 decades alone from Central America; who now dominate America's immigration.