For the reference and convenience of everybody else, here are the scriptures you referenced in 2 Nephi 25:
9 And as one generation hath been destroyed among the Jews because of iniquity, even so have they been destroyed from generation to generation according to their iniquities; and never hath any of them been destroyed save it were foretold them by the prophets of the Lord.
10 Wherefore, it hath been told them concerning the destruction which should come upon them, immediately after my father left Jerusalem; nevertheless, they hardened their hearts; and according to my prophecy they have been destroyed, save it be those which are carried away captive into Babylon.
11 And now this I speak because of the spirit which is in me. And notwithstanding they have been carried away they shall return again, and possess the land of Jerusalem; wherefore, they shall be restored again to the land of their inheritance.
I was unable to locate any specific sources where a living prophet warned the Jews about the Holocaust. But, I think there is a reason for that: the Jews have been in a state of apostasy since before the coming of Christ. They have been ignoring the prophets for a loooooong time. They were warned multiple times about their coming destruction and a curse upon their people. And, I think that they are just starting to come out of that curse.
Overall, they are among the many called... of which few are chosen. The call to the Jew and Gentile remains the same: come unto Christ. The qualifications for being the chosen people are the same. The Jews lost that position through apostasy.
What does that mean? Well, the creation of the State of Israel is NOT necessarily the gathering of Israel. In fact, as members of the church we should NOT blindly support this state. Zionism is a secular movement... and should not be considered The Gathering. In many ways, Zionism has been a terrorist movement. Personally I am reticent to interpret scripture as a reference to the State of Israel.
So, I will disagree with your analysis of verse 11. I think that return to the land of their inheritance is yet to come... both physically and spiritually. The house of Israel will inherit Jerusalem when it is worthy to inherit it. So, as members of the church, we stay neutral on anything involving the State of Israel. We are to treat the sons of Ishmael the same as the purported sons of Judah when dealing with political conflicts.
Elder Howard W. Hunter said the following:
"Our Father loves all of his children. He desires all of them to embrace the gospel and come unto him. Only those are favored who obey him and keep his commandments.
"As members of the Lord's church, we need to lift our vision beyond personal prejudices. We need to discover the supreme truth that indeed our Father is no respecter of persons. Sometimes we unduly offend brothers and sisters of other nations by assigning exclusiveness to one nationality of people over another.
"Let me cite, as an example of exclusiveness, the present problem in the Middle East---the conflict between the Arabs and the Jews. We do not need to apologize nor mitigate any of the prophecies concerning the Holy Land. We believe them and declare them to be true. But this does not give us justification to dogmatically pronounce that others of our Father's children are not children of promise. ... Both the Jews and the Arabs are children of our Father. They are both children of promise, and as a church we do not take sides. We have love for and an interest in each. The purpose of the gospel of Jesus Christ is to bring about love, unity, and brotherhood of the highest order."
"All Are Alike unto God," in 1979 Devotional Speeches of the Year (Provo, Utah: Brigham Young Univ. Press, 1980), p. 35.
In all conflicts, we are invited to be peacemakers. Sometimes war is necessary under specific circumstances. President Hinckley said during the April 2003 General Conference:
In a democracy we can renounce war and proclaim peace. There is opportunity for dissent. Many have been speaking out and doing so emphatically. That is their privilege. That is their right, so long as they do so legally. However, we all must also be mindful of another overriding responsibility, which I may add, governs my personal feelings and dictates my personal loyalties in the present situation.
When war raged between the Nephites and the Lamanites, the record states that "the Nephites were inspired by a better cause, for they were not fighting for ... power but they were fighting for their homes and their liberties, their wives and their children, and their all, yea, for their rites of worship and their church.
"And they were doing that which they felt was the duty which they owed to their God" (Alma 43:45--46).
The Lord counseled them, "Defend your families even unto bloodshed" (Alma 43:47).
And Moroni "rent his coat; and he took a piece thereof, and wrote upon it---In memory of our God, our religion, and freedom, and our peace, our wives, and our children---and he fastened it upon the end of a pole.
"And he fastened on his headplate, and his breastplate, and his shields, and girded on his armor about his loins; and he took the pole, which had on the end thereof his rent coat, (and he called it the title of liberty) and he bowed himself to the earth, and he prayed mightily unto his God for the blessings of liberty to rest upon his brethren" (Alma 46:12--13).
It is clear from these and other writings that there are times and circumstances when nations are justified, in fact have an obligation, to fight for family, for liberty, and against tyranny, threat, and oppression.
But, I would argue that the Israel-Palestine conflict does not fit this scriptural definition of a Just War... on either side. Both sides are wrong, both sides are right. And both are using religious arguments to justify their unrighteous position.
President Hinckley in October 2001 said:
"Religion offers no shield for wickedness, for evil, for those kinds of things. The God in whom I believe does not foster this kind of action. He is a God of mercy. He is a God of love. He is a God of peace and reassurance, and I look to Him in times such as this as a comfort and a source of strength."
And, Dallin H. Oaks has commented:
As we seek to understand the causes of wars, persecutions, and civil strife, we can see that they are almost always rooted in wickedness. The mass-murders of the twentieth century are among the bloodiest crimes ever committed against humanity. We can hardly comprehend the magnitude of the Nazi holocaust murders of over five million Jews in Europe, Stalin's purges and labor camps that killed five to ten million in the Soviet Union, and the two to three million noncombatants who were killed or who died of hunger in the Biafran War. (See Isidor Walliman and Michael N. Dobkowski, eds., Genocide and the Modern Age, New York: Greenwood Press, 1987, p. 46; The Nation, 6 Mar. 1989, p. 294, 7/14 Aug. 1989, p. 154.) All of these slaughters, and others like them, were rooted in the ancient wickedness Satan taught---that a man could murder to get gain. (See Moses 5:31.) The mass-murderers of this century killed to acquire property and to secure power over others. (Dallin H. Oaks, "World Peace," Ensign, May 1990, 71)
So, my point is, war is caused by evil. The Scriptures allow a Just War idea as a way to combat that evil, but only as a means of defense. But, when we are talking about prophecies of the Holocaust, there are significant prophecies in the scriptures that warned of a long, drawn-out dispersion of the House of Israel. And, despite the existence of a state named "Israel," that dispersion has not concluded. The curse is just beginning to be lifted. Now, it is up to all men to accept the Gospel of Jesus Christ to be worthy of any land of inheritance.
I tried to get a lot of thoughts into here... so I hope it makes sense. Overall, I could not find any modern revelation concerning the holocaust, except those calling it evil in the past-tense. But, the Jews have been ignoring the prophets for over 2000 years now. I think it all is part of the same curse. And, to be honest, I don't think the curse will be fully lifted until Christ returns to this earth in his glory. Until then, it is our job to promote peace and fight against evil. Tough job, don't you think?
That is all.