What if the underground utilidors from this teaser cycle and the HHN30 promos have held the beating heart of Halloween Horror Nights itself all along? Universal built the park on top of a sinkhole with an ancient eldritch being inside that requires the sacrifice of fear and screams each year from September to October in order to not destroy the park entirely, and that's why HHN exists. Or something like that, I don't know.
Maybe the utilidors are the Legendary Truth? or a new opposing group that has been feeding this HHN abomination for years now under the radar? Maybe it's the Legendary Truth feeding it because they've taken over by bad guys, like S.H.I.E.L.D. getting infiltrated by Hydra in Winter Soldier?
Or it could just be a marketing gimmick for a few promos that has no greater lore or in-event significance, that no one on the design team has thought very deeply about, kinda like the conspiracy theory stuff from 32's IP trailers. That's the fun thing about HHN lore, the rules are made up and the points don't matter.