It seems that Eidos Montreal are planning to bring back another franchise to go along with Deus Ex 3.

AAA games, with high quality licenses that offer exciting challenges - e.g., the first two games we develop will revive successful franchises

According to Rock, Paper, Shotgun investigation it could be Thief 4.

Another quote from the Edios Montreal site:

Eidos-Montréal is proud to announce the recruitment for our 2nd “AAA” project.
… A hint! The title begins with the letter “ T ”

Very intriguing, Tomb Raider has already been brought back from the dead so it seems to fit that it would be a new Thief game. Of course we all know full well the danger of looking too deeply into things like this, but the possibilities are certainly exciting!