Broader appeal to who? HM is a niche target. If the new movies underperforms or gets buried by TMNT (Releases the week after) why even bother?
They had the biggest movie franchise in history (STAR WARS) and still messed it up.
I don't think Haunted Mansion is a niche target to the fans who flock to the parks every year. That ride has staying power, people LOVE it. The movie has absolutely nothing to do with it's popularity.
We (just our opinion) would stay in a HM themed hotel even without any role-playing stuff. It would be just that fun. (If people want a pool, they can make it spoooooky). I do hope Disney would keep the price point more reasonable though.