WB themselves. Although I personally have my doubts. It's been 2 years (obviously one of those was a pandemic) and the event wasn't a smashing success as it is. Personally, I'd like to see WB properties back at Universal. The Exorcist and Beetlejuice are a big indicator that it's possible. And if that's the case, next year there are some HEAVY HITTERS that HHN still haven't touched that people have been clamoring for: IT and The Conjuring-verse would sell out the event every night with just those two.
Ya know what, I'm adding that to my official speculation. I don't have faith HMH will return!