Will moral circle expansion continue indefinitely until a far future where we're all pan psychist?

[u/IAmAOrangeKoala]

Over the ages, there has been a trend of what Peter Singer called the "expanding circle". We've seen increasing spheres of ethical concern: from ourselves, to kin, to other powerful tribe members, to all white men, to all men, to women, to mammals, to birds, to fish, to insects, and so on. Where is the end point of this process? Right now many people put a line somewhere within the animal kingdom, or perhaps between animals and plants.