OXM sources indicate the game will launch in 2013.
Thief 4 will skip the Xbox 360 and PS3, instead launching in 2013 for Xbox 720, reports OXM (via CVG).
The magazine's gossip section claims to have been told by reliable sources that Square Enix's Thief 4 is being re-worked for the next generation. This does line-up with an Eidos Montreal job listing for a next-gen action adventure game featuring "player choice" and "stealth".
Thief 4 is believed to have been in development for four years, with a designer already claiming to have completed the game's final level.
After so long in development we can't see this next generation version being anything more than comparable to the game running on high-end PC hardware, which would leave the option for Square Enix to also release versions for current consoles.