A couple of years ago the plan was to release an expansion for Saints Row: The Third called Enter the Dominatrix. Work on it was cancelled and instead that team moved over to work on Saints Row IV (that was already in development). Some ideas were retained and used in Saints Row IV. But Enter the Dominatrix wasn't thrown away and now it has been revealed that the once cancelled expansion will now be released as an expansion for Saints Row IV.
"The canceled Saints Row the Third expansion sees new life as the first DLC mission pack for Saints Row IV. In this alternate take on the Zin invasion storyline, Zinyak and the legions of his alien empire trap the Saints in a virtual world run by a mad AI program known as the Dominatrix. In order to thwart her nefarious schemes and escape to the real world, the Saints will have to counter her army of gimps and sex-workers, shut down her demented simulation, and make unlikely allies along the way. Includes behind-the-scenes commentary and the return of some fan-favorite characters."