Game Informer's April cover is set to reveal a Thief reboot:
"Eidos Montreal has been working for years to reboot the classic stealth series Thief, and the fruits of its labor will finally be revealed in issue 240 of Game Informer Magazine.
Series hero Garrett returns to the Gothic, industrial metropolis known simply as the City to steal any and everything that will make him richer. Unfortunately, the City is broiling with social tension as it is ravaged by a plague and lorded over by a political tyrant known as the Baron. In order to survive his adventures, Garrett will have to pay attention to his environment and make use of the ma[n]y possible paths through each of the game's levels."
The reboot is currently pencilled in for a 2014 release, and is a next-gen only title, with releases planned for the PlayStation 4, PC and 'other next-gen consoles'.
Source: [Game Informer]