It seems Bloodborne will be getting some new content, albeit in comic book form! Titan Comics has announced that they are creating a new comic book for the Bloodborne universe, set to release in February 2018. It’s unclear if Bloodborne: The Death of Sleep will take place during, before, or after the events of the game.
Here is the preview of The Death of Sleep’s cover:

GamesRadar has a bit more about the comic:
Bloodborne: The Death of Sleep will be written by Ales Kot (Generation Gone, Zero), with art by Piotr Kowalski (Wolfenstein, Dark Souls). As in the game, a nameless Hunter will step forth onto the cobblestone streets of Yharnam on a quest to rid the gothic city of its beasts and unholy aberrations. It’s not clear if the comic takes place before, during, or after the events of the game – but then, so much of Bloodborne lore is steeped in mystery and obtuse riddles anyway. In a press release, Kot said he was “obsessed” with the game, putting roughly 200 hours into it. “I am honored to be working within the Bloodborne universe,” Kot said. “There will be mystery, the weird, the eerie, the horrific and the bloody – and there will be an undercurrent of decaying romanticism, walking hand in hand with brain-mashing, soul-cleaving action, together ascending towards the Blood Moon as drawn by the talented and depraved Piotr Kowalski. Ascend with us, Hunters old and new. And do remember: one has to seek Pale...