I'm not sure right now the full extent of races will eventually become. I think it will just start out with the races already in the video game, which would be a good and relevant start for the Final Fantasy XIV TTRPG. I want to see stuff like the Qu, the Seeq, and Chocobo as playable races soon afterwards if they aren't already in the game.
I wonder if they will implement races such as the Moogle, any beast tribe races that aren't playable, and possibly even Ivalice based races such the Seeq as I think they appeared in Final Fantasy XIV before. Eventually they might expand I don't think they would go as far as making low powered versions of monsters like the Malboro, though there might be something like the Chocobuddy race from pathFinal Fantasy because Chocobos are a marketable part of the Final Fantasy franchise and I think people would be excited to be able to play as one. I don't think the selection will end up being restricted permanently to the playable seven or so races in the video game, and I hope it isn't that limited even at the end of the system's life.
I'm pretty sure they won't add races such as pathFinal Fantasy's Embodied race or the Palico race from Final Fantasy D20 because those aren't owned by Square Enix, and they would need to seek out permission to add to their systems.