You said the treadmill stops when you change public attitude, and you imply the terms Black and African American used to refer to black people are acceptable designations for groups of people as of now. I'm making the point that that is completely subjective, as in my case I don't like being referred to as an African American, because I'm not, and black is basically a synonym for "Not african american", yet these are the default terms and you say that there is "no further replacement". My point is that words change meaning all the time, we are not heading into some inevitable singularity where all of these words over here are objectively good in all situations and all of those words are objectively bad in all situations and this will remain so for eternity - language is not that stagnant nor black and white, and for me that is a good thing. It is 100% your personal opinion that you find the terms Black and African American acceptable designations for groups for the foreseeable future, but don't project your personal opinion onto others - I personally look forward to the day where people refer to me as Jamaican and not just "black" or mistakenly, African American, and in the same way there are those who hold the opposite opinion and those who don't want to be generalized at all. That you personally like or dont like a particular label has no bearing on whether or not everyone else agrees with your opinion.

Tl;dr your statement "The [euphemism] treadmill stops when you actually change public attitudes" actually means "The euphemism treadmill stops when you actually change public attitudes in such a way that I am personally comfortable with it's final state", because in reality the treadmill will never stop, someone will always push to keep it going, it's the reason why language shifts and changes over time.