Thief 4, now simply titled "Thief," has been confirmed as a next-gen title. Square Enix is planning to release the game for PC, PlayStation 4, and "other next-gen platforms" (i.e. Microsoft's box) sometime in 2014.
The confirmation comes from GameInformer, as the game is the magazine's next cover story. Garrett is back in the lead role, sneaking about a Gothic-styled industrial city known simply as "the City." The metropolis is suffering from a plague and ruled by a tyrant called the Baron.
We had heard rumors that the game was making the jump to next-gen consoles, but this is finally confirmation of the scuttlebutt. More details are sure to come now that the announcement is official.
Update - Eidos Montreal has also issued a press release regarding the announcement. "We're handling a precious gemstone with Thief," Eidos Montreal general manager Stephane D'Astous said. "Fans remember the original games very fondly and we want to preserve that essence which we have excellent experience of doing at Eidos Montreal, whilst also introducing Thief to a brand new, next-generation, audience. Our goal is to deliver the fantasy of being Garrett, the master thief, and we're building this game around that core experience."
Update 2 - GameInformer is starting to hit digital subscribers, shedding a few more details on Garrett's adventure. This game is being treated as a reboot, and is said to tone down the magical elements. Garrett will have a multifaceted and upgradable "Focus" ability to highlight climbing spots or drawers that hold valuables, or in combat to find weak points or chain attacks. Finally, the guard AI is aiming to be smarter than your average stealth game, as guards will be familiar with stage layouts and check around hiding spots. Check out the full issue for more details.