Really excited to see what they do with this (and bummed out I wasn't able to get a subscription in time).
This looks a lot like Disney's take on an alternate reality game. There is a vibrant - although small - community of people who are into puzzles and interactive real-life fiction events, and there's a lot of overlap between that community and the Disney fan community. If you've heard of escape rooms, that's another evolution of the same sort of idea that's gaining popularity. A few years back in 2012, one of the strongest groups of puzzle authors - a small company called Shinteki based in California - even hosted an unofficial puzzle event at
Disneyland:
http://www.shinteki.com/disneyfaq.html
The closest analogy for this Haunted Mansion subscription is the Black Letter Game - a service that mails you a puzzle on a regular basis to be solved in your home.
http://www.blacklettergame.com/ I actually thought the quality of puzzles from Black Letter Game wasn't all that great, though, so I think there's a lot of opportunity for Disney to do something amazing with this concept.
Thanks to Disney being a giant faceless corporation, you can get a good preview of what this HM themed event will entail by looking at the legal terms and conditions.
https://ghostrelationsdept.disney.com/game-terms/ There will be a mobile app called "Haunted Mansion: Phantom Radio"... and it will involve some actual physical interaction at the parks themselves, too.
Looking forward to hearing more! (And if someone at Disney comes up with an extra slot, I'd sure love the chance to get in on this!)