Could you elaborate on this? I wasn't around for 25 and this sounds .. quite interesting, to be honest.
I've always seemed to struggle with what exactly the definition of "speculation" is, because to be honest, there would be a "reason" for most IPs to come.
Not an expert on either topic so I'm sure there's more to add:
1. Scream at HHN 25 was at the release of the new show and was to be a promotion for it. If you've seen anything about the show, the first season mask is new and not immediately indicative of Scream. The rights to the costume are separate from the IP - Wes Craven wanted the costume to be something that anyone, like the killers, could just go buy from the store (This is why Dead by Deadlight has a Ghostface killer but isn't a licensed killer from Scream. You can get the rights to one without the other). What really caused issues however is that the house had no ties to the new show, and was entirely based around the first film. If you watch a walkthrough of the Purge that year its a one-to-one of film moments with different killers and Purge graffiti. It was a gambit by HHN to get an IP that they had wanted for sometime. Rights holders were NOT happy when they saw the final result and pulled the rights last minute, forcing Universal to do a quick re-theming.
2. That's not you're fault at all lol. Speculation imo needs to have a reason, whether is be related to:
Timing - new release, anniversary, etc
Rights - can the property be acquired, relations with IP holders
Desire - does HHN want it
Popularity - will it bring people to the event
Hints- has someone pointed signs towards it
Anything to base around why someone believes a property or theme will be coming. Something can still hit a few markers and still be absolutely just wishful thinking though. If there is a reason behind the belief, and evidence, and you can show it, it's speculation. That's where the fun of speculation comes from. Piecing together information and figuring out what awaits before the information is released to the general public.
I'm sure others have more to add, but that's the methodology I follow at least.