User blog comment:LilyheartsLightning/Citadel and Reckoning DLC announced/@comment-1440333-20130223235541/@comment-24174486-20130224013808

Given the plot and location for the DLC, it seems unlikely that Cerberus would be able to serve as the enemies of the DLC.

There's also this image showing unknown troops equipped with a Saber and Tempest, which could be new enemies for the DLC.