It's strange to see my old mods actually living on, thank you (and Sladki?) for taking care of it.
I invited you as a collaborator if you'd like to upload new versions for the original mod. If you'd rather prefer to continue uploading here I'm absolutely fine with it and I'll even add a link on the mod page of BNW to BrNW(?). If you opt for the collaborator way, should I invite Sladki as well?

Sladki has done some work. I've done some. Less than is really warranted I fear. There are a few things that should be fixed that I haven't gotten to.

I would love to migrate this to Brave New World. This weird cycle that shows up in the Factorio mod community of mods being developed, then sort of abandoned by the original developer is vexing to me. I don't think the original developer should be forever on the hook, but there needs to be a better way to pass on the keys. I've taken a number of mods under my sort of disinterested wing just to keep them alive enough for someone else (hopefully) to take them over.

I agree. I don't think it's possible to have multiple ownerships for a mod, so unfortunately it's difficult to pass on the keys as you say. I can add collaborators and even pass ownership, but in the end it's still only one person that can pass on the key.
My other popular mod, Auto Research, was patched by SirTony. For this mod I created a new Github repo, gave SirTony access to it, committed the last version I published and committed all the versions SirTony published. I can do the same for BNW, does this sound good to you?

I cloned your Brave New World Github repo. I can submit a patch request, and if you like you could add me as a maintainer there.

Oh, now I remember, you had a mono-repo for all your Factorio mods. Hmm.... Do you want to just clone mine? I cloned yours them just removed everything not BNW related and moved all the files down a level.

https://github.com/Omnifarious/Braver_New_World

Yeah, the mono-repo was a bad idea (but it was "easier" at the time...).
The history of that repo is kinda a mess, but I guess it's rather irrelevant (who checks it anyways). Might be an idea for me just to pull in your changes and rename the repo (not sure how that'll affect those who've cloned my mono-repo, though). Or just create a new repo. Probably better idea, I sort of want to get rid of the old repo, but renaming it is probably just confusing.

Mine still has the history from your mono-repo. I made all the changes within the repo. I could use Mercurial's marvelous convert extension to erase any parts of the history that don't effect Brave New World and to also act like the files were always in the top-level directory.

I looked into preserving commit log for only BNW from my mono-repo, but I couldn't get it pretty.
It's not likely that I'll spend much time working on this mod in the near future, so I'm fine with the mod living on in your repo. Cloning your repo just to make a dedicated repo for the mod when you already have one seems pointless (and I don't really need to "own" the repo).

Sounds like a plan. :-)