Did Sauron have a successor?

In this video, we learn if Sauron had a successor. If he didn't, what troubles would they have faced in a fallen Mordor? If he did, who was it, and why didn't they take control? Thanks to my patrons - Habimana, Ben Jeffrey, Harry Evett, Mojtaba Ro, Moe L, Paul Leone, Barbossa, mncb1o, Carrot Ifson, Andrew Welch and Catherine Berry. Patreon - www.patreon.com/darthgandalf/