Yes Eta is a long shot, but I hope the success of a GHCJS merge (which I think would be enormous) could build some momentum. I left a comment in https://github.com/typelead/eta/issues/984#issuecomment-761232613 saying basically that the Haskell Foundation’s existence should address the stated issues why Eta forked in the first place.
I would not at all be opposed HF funding @rahulmutt to get the the backend resurrected and merged upstream. I know there is a bad taste in many of our mouths over the fork happening in the first place, but IMO getting ETA merged would be awesome and make me feel “all’s well that ends well”.
(Lastly, GHCJS, Asterius, and Eta I believe all work from STG, so I think there could be some good synergy underneath the hood really fleshing out “backends from STG” abstractions, etc.)