It's been confirmed that an expansion for Bloodborne will definitely be coming in the future and From Software are already going over ideas for new content. Unlike many other games these days, Bloodborne did not come with a season pass from day one so players have been curious about the developer's DLC plans.
Whilst there weren't any definite plans for future content in the past, Shuhei Yoshida has confirmed on Twitter that an upcoming expansion will be coming for Bloodborne. Unfortunately not many details have been shared so far, but Yoshida has mentioned that more information will be shared later this year.
Considering that Shuhei Yoshida is Sony Computer Entertainment's World Wide Studio's president it's pretty clear that this information can be trusted and a Bloodborne expansion is definitely coming.
It's definitely a smart move by both Sony and From Software to plan more content for Bloodborne. Even though Bloodborne is a PlayStation 4 exclusive, it has managed to pull in enough sales to rival many other new gen only titles. Bloodborne also managed to exceed Sony's original expectations for the game, which is saying a lot because Sony were originally quite ambitious about Bloodborne.
For the time being though we'll have to make do with the current game and any minor patches that may be released periodically over time. Hopefully somebody from Sony or From Software will reveal more information about their plans for future Bloodborne content rather soon. I'm sure if you enjoy the game as much I have you'll be excited to hear any news about Bloodborne.