This has not been officially confirmed by Blizzard, but in a BlizzCon schedule which has since been taken down, one of the events during BlizzCon is called “Hearthstone: What’s Next?” in which attendees are invited to “hear a tale of adventures yet to come!” Given Blizzard’s penchant for teasing, this does hint that a new Hearthstone adventure could be announced.
For those unfamiliar, there are two types of Hearthstone expansions. Some expansions like The Grand Tournament and Goblins vs Gnomes are mostly card expansions meaning that they will introduce a host of new cards. Then there are also Adventure-style expansions which offers up solo play and basically quests/missions for players to complete, like Curse of Naxxramas and Blackrock Mountain.
Based on Blizzard’s wording, there is a good chance we could be looking at an Adventure-style expansion here, especially since the previous release was The Grand Tournament. Either way do remember to check back with us during BlizzCon 2015 next month for the details.