According to a report on Kotaku from internet sleuth Superannuation, not only did audio director and composer Paul Weir leave Eidos Montreal, but so did lead level designer Adam Alim, senior concept artists Nicolas Ferrand and Dan Blomberg, senior technical level designer Eugene Kuczerepa, senior animator Marie-Chantal Larocque and senior level designer Patrick Garon. In addition to the departures, there's also apparently a completed CG trailer created by Goldtooth Creative – the same firm responsible for Deus Ex: Human Revolution's CG and cutscenes – that never saw the light of day, and was planned for a December 2011 unveiling, according to this resume.
So what could be the situation? One level designer still at Eidos Montreal says he designed the last level in the game – take from that what you will. In light of all this, we've followed up with Eidos Montreal and Square Enix for official comment.