Nelson's recent BYU speech was edited, post delivery, to remove the line "God has not changed his definition of marriage" from the talk. I think it fair to assume the revision was absolutely necessary -- to avoid confusion or accusations of dishonesty -- due to polygamist doctrines and practices (both historic and as presently allowed for in the temple). It especially merited editing, ironically, since this portion of the talk appeared immediately following such bold declarations as "we [prophets] are commanded to teach truth" and "we [prophets] will always teach the truth!"
I highlight one section from the revised text because it could, potentially, be viewed as leaving open the possibility for an anticipated future revelation changing to the definition of heavenly sanctioned marriage.
Emphasis added by me.
Nelson wrote:For example, let’s consider the definition of marriage. In recent years, many countries, including the United States, have legalized same-sex marriage. As members of the Church, we respect the laws of the land and abide by them, including civil marriage. The truth is, however, that in the beginning—in the beginning—marriage was ordained by God! And to this day it is defined by Him as being between a man and a woman.
Again, we know this segment of the talk was edited before online publication.
Therefore, the wording will certainly have been carefully reviewed and re-reviewed for clarity and intent.
Nelson didn't have to add "to this day" as a qualifier. He could have been significantly more definite -- "It is defined..." or he could have sealed the deal forever with "It is and will always be defined..."
But he didn't. He instead made the statement as indefinite as we have ever seen. "To this day, it is defined..."
I would cautiously proffer that Pres Nelson just quietly left a window open. If he did, and if he meant to do it, then why? Is it possible that through the crack is visible, for the first time in church history, a prophetic hint at the path leading to adoption of full marriage equality in the church?
I'm sure there will be plenty of opinions on this matter. And unfortunately, if history rhymes, we won't know the answer for another decade, or two, or three.