Earlier quoted context omitted.
This is just the euphamism treadmill in action. The name for an outgroup becomes a slur over time because it refers to an outgroup.
The treadmill stops when you actually change public attitudes. African American/Black have been the main terms in American language for 50 years now, with some back and forth between the two, but no further replacement.
I'm not aware of any societies without outgroups, are you?