This tracks what I've seen, would just say (based on following along on these forums, Discord, and Reddit, and based on zero insider information):
-Evil Dead Burn is definitely rumored, but I keep reading persistent skepticism that it, as well as Ozzy, are actually coming.
-The specifics of the original houses seem to be mostly unknown still. For example, I recall Legacy saying that it is just spec that the makeup symbol on the maps would be tied to Bzzcon.
-I think it's unclear whether the New York zone will be IP-based or not (based on, for example, the fact that the latest spec map used the generic clown symbol and not the alien clown or trash bags from the Hollywood map that signify KKFOS and Terrifier)
-Mel's DIE-In would be a "street experience" again, and the latest spec maps also suggested Club Horror will be back
-The latest thing I read is that it's unknown whether the Lagoon Show will be Stranger Things-specific versus more general