It didn't make it for the previous installment, but it's still coming.
Publisher Deep Silver has announced that the Enter the Dominatrix DLC for Saints Row IV will be available in North America on October 22, and a day later in Europe. It's included with the $10 Season Pass and will be sold separately for $7.
This expansion was originally intended for Saints Row: The Third but after THQ went down, those plans were scrapped. Now, evidently, that same add-on is is ready to go for SRIV; the second piece of DLC, How the Saints Saved Christmas, is scheduled for later this year. Enter the Dominatrix is an alternate spin on the Zin invasion narrative, where Zinyak and his alien buddies imprison the Saints in a virtual world run by a crazy AI program. And of course, the name of that program is the Dominatrix.
Not that there's any pun intended or anything.
Related Game(s): Saints Row IV