If you have nothing to offer a country, why would that country accept you except under extenuating circumstances (ie political asylum)? You must be able to contribute in a meaningful way.
EDIT: Shifting from a biological to a cultural explanation for why certain racial groups have inferior/unacceptable behaviors doesn't diminish the level of racism. Country of origin dominates any measure of individual assimilation w.r.t your chances in the immigration system, so it's not clear that shifting the rhetorical justification changes anything either.
Of course that country still exists. We're all sitting here benefitting from it while we kick the ladder on everyone else.
Maybe not, if the selection process were primarily concerned with individual merit. But it isn't. We decide which races to allow as residents or citizens, then throw the individuals into a lottery, with good odds for white countries and bad odds for brown ones. Discriminating on ancestry or proxies for ancestry (like nationality) to keep underprivileged groups down and privileged groups comfortable is immoral. So is denying others the same opportunities benefitted from merely because they came later.
Would your own family tree's entrypoints to the US pass your test?
Concern about the "challenges" of too many brown people in your country is usually just called "racism."