Bruce R. McConkie says polygamy will come back after the Second Coming.
Bruce R. McConkie, Mormon Doctrine (Salt Lake City: Bookcraft, 1958), 522–523
After Brigham Young led the saints to the Salt Lake Valley, plural marriage was openly taught and practiced until the year 1890. At that time conditions were such that the Lord by revelation withdrew the command to continue the practice, and President Wilford Woodruff issues the Manifesto directing that it cease. (Discourses of Wilford Woodruff, pp. 213–218.) Obviously the holy practice will commence again after the Second Coming of the Son of Man and the ushering in of the millennium. (Isa. 7.)