Same boat as Deus Ex 3 to my knowledge... Some big cock-ups at Eidos Montreal over the past year or two with designers coming and going has meant both the Thief and Deus Ex series seem to be on a seemingly endless hold... Unless it's all sorted and they're just biding their time as part of a brilliant marketing ploy.
Sadly I doubt it.
YouTube- Deus Ex 3 Human Revolution GDC Teaser Trailer from GDC 2010. HD