People who do not understand evolutionary ideas believe there is some kind of "stasis" or "completed" stage they want to adopt as a wooden abstraction.
There is no such thing.
Particularly in high population environments, there is no neutral model. A species is either growing more specialized or less specialized. If someone tells you that eugenics is now so disadvantaged that it is no longer possible, what they are telling you is that species is now in a dysgenic environment ... which is part of the extinction cycle that produces specialization. So even a dysgenic state will return equilibrium to a eugenic selection in time.
Or simply wipe that species out altogether.