I'm not advancing that argument at all, but rather arguing "even people who do believe that will surely agree that the USA will someday cease to exist and, later, will fall out of history to an extent that someone will have to ask who/what the USA even was and, therefore, the notion that we will forever need affirmative action because '[the USA had] an actual legacy of the extraction, relocation, and enslavement of a particular group of people on the basis of race' is highly questionable".

I see. We're misunderstanding each other.

A society with severe imbalances in wealth, health, and power should examine how those imbalances came about. If it turns out that they're directly caused by racism, that society should consider race-conscious remedies. This is true regardless of how long the racist policies have been perpetuated, and it's true regardless of whether or not the federal government of the USA still exists.

I agree with that 100%!

My only disagreement was with the conclusion that such remedies should be ordained at this moment to be "always be a topic deserving of special dispensation" since always is a very/infinitely long time.

I never said it should be ordained for all time. I said it should be ordained until the issue is solved. If that takes another hundred years, we shouldn't just stop because too much time has passed - in fact we should probably double down and accelerate our efforts in that case.

You didn't (nor did I suggest you did); someone else did; that's what started this sub-thread.