The channels on the TV that Susie flips through show a cooking show, a weather report, and a kaiju film. She also namedrops some silly horror films. Just going by that, I feel like we won’t have to worry too much about the next chapter retreading too much ground (though anime seems inevitable (though it could possibly be in the service of letting Undyne know anime is real (hmmmm…))). Regardless, what I’m most excited to see is the (hopefully horrifying) off-brand Yoshi from Super Smashing Fighters.
Regarding your second paragraph there, I don’t think anything about sans (and, by extension, Papyrus and [REDACTED]) needs to fit neatly into that theory. sans, being sans, could easily find his way into Asriel’s version of Undertale — I mean, his storefront is literally Grillby’s place from Undertale with the name scratched off, so even if the Azzy’s unfinished game is just a twee meta-joke I don’t think it’s off-limits for sans.
Oh, and while I remember it, the virovirokun virus enemies first appear after the arcade machine (so a while after we see Noelle get captured) but before we fall down to the city and team up with her, so I don’t think their presence is related to Noelle’s dad. (I just took them as references to niconico and computer viruses (the librarby needs to update their firewall imo).) On the other hand, I think the other health-related enemy does appear after we first team up with Noelle (though I forgot what it even is lol).
Oh, and while I’m thinking of Noelle — the calendar in the room the queen gives her, where every month is December and every day is Christmas — I’ve heard someone guess that that’s there because she searched for “December Holiday” repeatedly. December is implied to be the full name of her sister Dess, and it’s fairly clear that something tragic happened to her. Given that Noelle searched for her name over and over, it’s more likely that Dess went missing rather straight-up dying (perhaps she went missing in the dark world somewhere in town (like the bunker)). My only issue with this theory is that, between Dess and Rudy and her mom, it almost feels like it lumps too many future plot developments onto the Holiday family (counterpoint: there’s still 5 more chapters).
Speaking of things going missing, I recently checked out the Undertale page on TCRF and found out that nearly all of the Gaster-related content on that page had mysteriously disappeared. Apparently (according to the talk page) it was removed on the basis of it just being extremely ephemeral, and thus technically not unused. tbqh I can’t think of a more fitting fate for that information.