I'll always be cautious when it comes to refreshes of shows that I enjoy, but this certainly makes sense. I do really like HMUS, but it is nowhere near perfect. As others' have noted, The Mummy (2017) takes up a good portion of the show runtime haha. In some ways, we are already in "the bad timeline" for the show's writing, and it seems to be doing just fine, almost entirely off the backs of the very charismatic improv performers.
Swapping in some new bits and gags certainly wouldn't hurt! The performers do really wonderful work, but there's only so many times you can loop the same exact gags and keep the energy, especially for a smaller and more intimate live show like this.
I totally understand that FNaF isn't exactly "make-up", but as a fan of the games from the very start, I can't explain how surreal it would be to see Fredrick Fazbear himself referenced in a permanent Universal Studios attraction haha! I am hoping we get at least an appearance within the "Best Of" montage segment or something.
I also agree with some others here that Darkmoor could probably show up towards the end of whatever Classic Monsters segment they put together. "... these films and the artists that worked tirelessly on them have left a legacy that lives on until this day!", and then showing quick footage from Unchained, or something like that. That would make sense for a company trying to hype up a new Horror-themed park.