D&D + Final Fantasy XIV = $$$
FFXIV is one of the few major MMOs experiencing active, sustained growth. It's beloved for its story and has tons of market exposure. The Final Fantasy series is already heavily D&D-like as it is, so there would be less need for massive adaptation. Square Enix has big pockets, and is pretty clearly interested in raising awareness for FFXIV, given the massive advertising push they put out for the Shadowbringers expansion. Plus, it's very clear that the dev team includes people who play D&D and other tabletop games.
I legitimately do not see how this wouldn't be a huge money-maker for WotC. There's a TON of fan goodwill from FFXIV that can be tapped into, and the game is currently going through its boom times. At the very absolute least, you could drive up sales/interactions/etc. with D&D products by working on some kind of collaboration or in-game event, since FFXIV loves its crossover stuff (having crossover events/content for FFXI, FFXV, Dragon Quest X, Yo-Kai Watch, Garo, Monster Hunter World, and Nier Automata.)