I'm in the throes of my monthly BGW obsession period, just measured the show buildings for Project 2027 and some other dark rides on Google Earth. Apologies if this experiment has already been done.
Phantom Theater - King's Island: Uses about double the 2027 building
Haunted Mansion - WDW: About 4x the size of the 2027 building
Danse Macabre - Efteling: Would fit perfectly in the 2027 building
Maus Au Chocolat - Phantasialand (Toy Story Midway Mania Style with Only 1 track): About 1.5x the 2027 building
I was expecting/hoping for a tracked dark ride but now I'm not sure it would work unless they did multiple floors. And even if they did, I'm not sure the ride would be very substantial. I'd rather they save a tracked dark ride for a Black Forest expansion by BBW. My new unrealistic hope is an Intamin Dynamic Motion Stage, which if done well with an ancient celtic theme could be one of the best dark rides/flats outside of Disney/Universal in the country.
I expect those in the know know more than we know they know, I'd love to know what they know soon, if you know what I mean.