Have you played the game? If you had you would know how big the map is and how varied the terain is you would realise this is nowhere near dlc quality or size. I doubt it ever started as a dlc idea either

Valley of the Yetis was fun while it lasted (About 3-4 hours I recall). The yetis were tough to take down until you find their weakness.I would love something similar dlc on Primal. Maybe a lost valley of dinosaur’s would be awesome but I think they will save that for later games in the franchise