Fandom does care about cash cows, and will almost certainly do the same thing they’ve done with several wikis that have left: take it over, remove references to the move, and continue attempting to compete with the new wiki, leveraging their better SEO.
But if anything, Fandom considering Memory Alpha a cash cow would be even more of a reason to leave, considering that Fandom tends to cover those wikis with ads (that’s why Minecraft Wiki moved).