*blows the dust off account*
Frankly, I feel that it is pretty obvious that as far as content Wowpedia is now vastly more developed and if one wiki should be shut down it will need to be WoWWiki. Just getting that out of the way and trying to speak objectively there. Trying to get the content on WoWWiki up to date would just be an utterly monumental task. And moving Wowpedia as a separate wiki back to the Fandom platform would similarly be folly.
That said, there may be some older data, mainly pictures, from vanilla WoW that were later replaced/deleted that are now irretrievable on Wowpedia that we now want back (for WoW Classic mode) and I might expect WoWWiki could be beneficial in that respect.
I also had the idea that WoWWiki could be re-tooled to focus more on fan-developed content. Certainly Fandom's community tools would be a more conducive experience to that goal.
Finally, I don't think we should need to feel any pressure from Fandom/Gamepedia to merge/close one wiki. But I do believe WoWWiki's days ought to be numbered. Splitting the community isn't great, especially when one wiki is fairly well maintained for current content and the other... well...isn't.