The return of Bloodengutz, please god. That's the one Original that will make me go full on crazy. Im surprised the sequel isn't already a thing. I wouldn't care what else was there if HR was at the event this year. I don't know how probable it is but now reading that @Legacy said that Slaughter will not appear gives me some hope that it will return because there concepts are familiar and having them both on the lineup is kind of a stretch.
Legacy just said he doesn't think SS will happen because the rumored lineup already has three clipshow houses. If SS doesn't happen due to that, then H.R.B. is in the same boat because that's another clipshow house. Only probable chance would be a cameo in a anniversary house, but I wouldn't see a full house being likely.