Yes, that's true. But that still doesn't change the words. Just because the revelation was given in response to that question, and that it deals with plural marriage, it does not make that practice the "new and everlasting" part of the scripture. Look at the sentence again. The phrase "new and everlasting" modifies the noun "covenant". It's the covenant that is "new and everlasting", not the practice of plural marriage.
Those plural marriage covenants will be eternal, just as any other valid marriage for time and all eternity.
That section of the Doctrine and Covenants still doesn't say that the practice of plural marriage would be "new and everlasting", no matter how you spin it.
Welcome to the ever-changing world of Mormonism....I am so thankful I now worship a God that is unchangeable....
In 1866, Brigham Young forcefully stated, "We are told that if we would give up polygamy--which we know to be a doctrine revealed from heaven and it is God and the world for it--but suppose this Church should give up this holy order of marriage, then would the devil, and all who are in league with him against the cause of God, rejoice that they had prevailed upon the Saints to refuse to obey one of the revelations and commandments of God to them." Later in the sermon President Young asked, "Will the Latter-day Saints do this? No" (JOD 11:239).
That same year, John Taylor, Mormonism's future third president, accused those who opposed polygamy within the LDS Church as "apostates." He said: "Where did this commandment come from in relation to polygamy? It also came from God...When this commandment was given, it was so far religious, and so far binding upon the Elders of this Church that it was told them if they were not prepared to enter into it, and to stem the torrent of opposition that would come in consequence of it, the keys of the kingdom would be taken from them. When I see any of our people, men or women, opposing a principle of this kind, I have years ago set them down as on the high road to apostacy, and I do to-day; I consider them apostates, and not interested in this Church and kingdom" (JOD 11:221).
In 1869 Wilford Woodruff, Mormonism's future fourth president, taught, "If we were to do away with polygamy, it would only be one feather in the bird, one ordinance in the Church and kingdom. Do away with that, then we must do away with prophets and Apostles, with revelation and the gifts and graces of the Gospel, and finally give up our religion altogether and turn sectarians and do as the world does, then all would be right. We just can't do that, for God has commanded us to build up His kingdom and to bear our testimony to the nations of the earth, and we are going to do it, come life or come death. He has told us to do thus, and we shall obey Him in days to come as we have in days past" (JOD 13:165 - p.166).
Even as late as 1879, Joseph F. Smith was insisting that plural marriage was essential for LDS exaltation. Speaking at the funeral of William Clayton, Mormonism's future sixth president, stated, "This doctrine of eternal union of husband and wife, and of plural marriage, is one of the most important doctrines ever revealed to man in any age of the world. Without it man would come to a full stop; without it we never could be exalted to associate with and become god..." (JOD 21:9).
During a message given in 1880, Mormon Apostle Orson Pratt said, "...if plurality of marriage is not true or in other words, if a man has no divine right to marry two wives or more in this world, then marriage for eternity is not true, and your faith is all vain, and all the sealing ordinances, and powers, pertaining to marriages for eternity are vain, worthless, good for nothing; for as sure as one is true the other also must be true." (JOD 21:296).
Hbr 13:8 Jesus Christ the same yesterday, and to day, and for ever.
Hbr 13:9 Be not carried about with divers and strange doctrines. For [it is] a good thing that the heart be established with grace; not with meats, which have not profited them that have been occupied therein.