Although it's not confirmed, it's a safe bet to assume Dialga, Palkia and Giratina are gonna be available in Legends Arceus (maybe in the post game?). So, I think there's a possibility we could travel to their specific dimensions for the battles. I'm not so sure about Dialga and Palkia dimensions, but the Distortion World is very likely to be included, since a smaller version appears on BDSP.
Also, it's highly likely the endgame revolves around the main character climbing Mt. Coronet in order to fight Arceus and/or the villain of the game, considering there's no Pokémon League. The climatic final battle is probably going to take place in Spear Pillar or even the Hall of Origin, which would be great.
Anyway, I'm excited for this because I really like the atmosphere and the mistery surrounding these locations, so it would be nice to visit them with the PLA graphics. What about you? Any thoughts about the endgame of Legends Arceus? Do you guys think Spear Pillar, Dialga and Palkia's dimension, the Distortion World and/or Hall of origin are gonna be included in the game?