Note that the old Fandom runescape wiki is still live. But the move to runescape.wiki was "successful" because it now sits above Fandom in Google search results.
Other splits are not so successful... Even really old ones like UESP, which predate Wikia.
That is precisely what happens.
See, for instance, Runescape's move: https://runescape.wiki/w/Forum:Leaving_Wikia
Note that the old Fandom runescape wiki is still live. But the move to runescape.wiki was "successful" because it now sits above Fandom in Google search results.
Other splits are not so successful... Even really old ones like UESP, which predate Wikia.