The case I found more worrisome is you follow someone, they then start using a new domain, and now it seems you're following a different handle (IDK if handles are immutable in Twitter, maybe they are not?).
Maybe BlueSky could offer a registrar that would do steps 1 & 2 for you transparently upon domain purchase.
Ah sure, that could be confusing -- though I believe Twitter allows you to change your handle as well. We could probably try to let people know when a handle changes, but we'll wait to see if it causes a problem before we get into it.
If there is not a mapping to some sort of immutable handle, i imagine some sort of announcement in the timeline(example.com has changed their handle to example.xyz) and a history in their profile (handle = example.com 2017 to 2020-01-01. example.xyz 2020-01-01 to now) would cover it
Ideally you could use the domain as a (vanity) pointer to an immutable handle and when someone follows the domain they'd actually be following an immutable identity that's a combination of the domain + immutable handle which reference each other.
example.com <--> ryan29-abcdef
I was trying to explain how I'd do it for a package repo a few months back.
You can change your handle on Twitter, but it's not recommended if you have any "follow me on Twitter @soAndSo" links out in the wild, because it opens people to handle squatters taking your old handle.
Maybe BlueSky could offer a registrar that would do steps 1 & 2 for you transparently upon domain purchase.