Every once in a while I hear someone speculating about polygamy and the millennium. But no one points out the very obvious answer, so I will just quickly note it.
In an article of faith we read that “Christ will reign personally upon the earth”. The resurrection will precede the millennium, and in the millennium resurrected beings will interact with mortal beings, for otherwise how can a resurrected Christ reign personally upon the earth? In fact, we read:
Jude 1:14 And Enoch also, the seventh from Adam, prophesied of these, saying, Behold, the Lord cometh with ten thousands of his saints,
15 To execute judgment upon all, and to convince all that are ungodly among them of all their ungodly deeds which they have ungodly committed, and of all their hard speeches which ungodly sinners have spoken against him.
Thus resurrected beings will interact with mortals ones. The earth with have a resurrected being as its king.
And Joseph Smith will walk again upon the earth. And Brigham Young. And Wilford Woodruff. And many other prophets and apostles. Even Joseph Fielding Smith, who was never polygamous in mortality, will be resurrected with his three wives, and walk the earth as a polygamist in the millennium.
So yes, it is blindingly obvious. There will be polygamists on the earth in the millennium. For the resurrection will precede the millennium.