I recently produced an essay where I argued that Disney could use projection mapping inside attractions to give them holiday overlays at the Magic Kingdom. For example, for the 2019 Mickey's Very Merry Christmas Party, Disney introduced Christmas lighting and music to space mountain, so why not take it a step farther and use projection mapping to create a more in-depth atmosphere or even a loose storyline? The same could happen for a version of the Haunted Mansion Holiday, and obviously it wouldn't be as in-depth as the one in California, but I think it's feasible. I understand that Walt Disney World doesn't do holiday overlays because it's a "once in a lifetime" destination, but I think creating unique attraction experiences for the parties could be a selling point for them. Considering that one of the original selling points were reduced crowds and that's clearly not the case anymore, making the parties more unique should be something that the company could go with, especially since anecdotally, I can say that it's been my observation that people are seeing the parties as less and less value.