I think the idea of revolving the whole plot around the Dyad makes way too much sense. Suddenly Palpatine has a clear plan that doesn’t involve Rey killing him and his spirit passing into her, Kylo has something to reveal to Rey in the hangar that isn’t her being a Palpatine, and presenting the Dyad as inherently part of the Dark Side (even if that turns out to be untrue) sets up a decent dilemma on whether or not Rey should kill Palpy to take his throne if it means turning to the Dark Side.