In my draft reply, I was going to add "is this even the right question", meaning "is the taxonomy more of a human construct than a natural one". It seems the answer is yes.
>Or groups that are in some sense different from other domains to the same degree those domains are from each other?
I'm not a biologist, and especially not a microbiologist, so you should take what I say with a decent chunk of salt. That said, microbes are so wildly diverse that that version of the question sounds a lot like "are there any big extinct clades of microbes", which, I don't know, microbes are pretty persistent. But probably.
As for macroscopic life, there are some Ediacaran critters like rangeomorphs and tribrachidium that (to my knowledge) are not conclusively associated with any existing domain. So who knows about those guys.
>Or groups that are in some sense different from other domains to the same degree those domains are from each other?
This.