WMG / Anno Dracula

Notes on Mad Scientists
Every book continues a Running Gag where we meet two Mad Scientists who study vampires, only one of whom will live to the next book. Candidates for the next one to show up:
  • Hannibal Lecter. Because Why Not?
  • As another possibility for a vampire psychiatrist, Hugo Strange. Batman's already been mentioned a few times. (Kirk Langstrom in The Bloody Red Baron, anyone?)
  • Jossed; Pretorius goes it alone in book 4. There's still Daikaju.

When we finally meet vampire elder Joshua York, he will make references to Game of Thrones and Wild Cards

Less a guess than a hope. Still, more oblique references have been made.
  • Maybe "aces" and "jokers" will be terms referring to higher and lower bloodlines, respectively?

In-universe, drinking vampire blood will become the inspiration for the Rossum Corporation from Dollhouse
We've already seem from Winthrop (and possibly Bond) that driving vampire blood can alter someone's personality. So in this universe imprinting will just be a matter of feeding someone vampire blood.

Dracula came to power because Sam Beckett accidentally leaps into one of Van Helsing's accomplices and screws up
There wasn't any indication of that happening in Dr. Seward's records, but then, he's going insane (maybe a result of being Leaped into?)
  • If not this, Sam Beckett will still be involved- as Beckett the vampire archaeologist.

In a future book, the Dixon brothers from The Walking Dead will be blended with Supernatural's Winchesters
Just as Leatherface's family became the Beverly Hillbillies

Daikaiju will be an alternate version of the last chapter of Newman's Seven Stars
The latter was a cyberpunk dystopia where a new batch of Biblical plagues arose that included a "plague of Godzilla". There's your daikaiju right there, and we know the fifth book is supposed to be set in a cyberpunk setting.