Eternal Darkness fills a niche that Nintendo doesn't really have much of, especially if Resident Evil misses their platform. Geist would be an interesting choice too as it's their best FPS IP. We talk about these types of games in regards to Retro because they are Nintendo's only (first party) western studio, so they should be more suited to making "western" style games.
I still think StarTropics as a Tomb Raider/Uncharted type game would be the most impactful "western" style game they could make. It's a genre Nintendo really doesn't have at all.