I can definitely see expansions coming - an "Eldritch Horrors" one, covering the Forbidden Forest (Snake men, Snake bundles, Kin bipeds, Giant Pigs, Shadows of Yarnham boss), Byrgynwerth (Garden of eyes, brain suckers, Celestial Centipede, Rom) and Ya'Arghul (Undead Amalgam, Snatchers, Chime Maiden, Mobs, One Reborn) and one covering the "Nightmare Realms" - Lecture building (student ghosts, executioner, Patches), Nightmare Frontier (Silver Beasts, Yetis, Winter Lanterns, Amygdala) and Nightmare of Mensis (Mergot Chief attendant, Mergot Attendants, Micolash, CrowDogs, Shadows, Wet Nurse).There is certainly expansion add-ons incoming, given how little the main game covers and the chalice dungeon material seems to be the main gameplay addition focus for stretch goals.
Other expansions possible imo: Hemwick + Cainhurst, and of course the Old Hunters expansion.
Dam that could be expensive when all is said and told...
The next goal is Eileen! Pledge you Cowards! ;)