"And now behold, my beloved brethren, I would speak unto you; for I, Nephi, would not suffer that ye should suppose that ye are more righteous than the Gentiles shall be. For behold, except ye shall keep the commandments of God ye shall all likewise perish; and because of the words which have been spoken ye need not suppose that the Gentiles are utterly destroyed."
This is troubling if you understand what is said here. Let's see if we can pull it apart.
Nephi adds this direct comment to his descendants, the forebears of the remnant. Although they are the target of covenants and beneficiaries of the restoration, they too need to keep to the path. Though they are "beloved brethren" to Nephi, they are not given any unconditional promises. No one is. Everything we receive is based on what we do, think and say. (See both Alma 12: 14 and D&C 130: 20-21.)
Note that this is not about the actual remnant, but about the Nephites who would be destroyed. These people would have access to Nephi's record until the time of Mormon, when they would be destroyed. You can see the time frame in the word usage, "Ye are" as to the Nephites, in contrast to "the Gentiles who shall be." This message is addressed to the Nephites in a time before the gentile.
What is particularly distressing is the comparison Nephi is making. He is saying that the Nephites, who possess the land of promise, needn't think themselves "more righteous than the Gentiles shall be" because if these Nephite descendants do "not keep the commandments of God" then they "shall all likewise perish." If the Nephites do not keep the commandments, they will, like the gentiles, perish.
This means that Nephi is confirming again his prophecy of the destruction of the gentiles. They are doomed. And the Nephites are similarly doomed unless they are obedient.
Despite this warning we know what happened to the Nephites. They were destroyed. The gentiles will be destroyed also.
In the case of the Nephites and the gentiles, "ye need not suppose that the Gentiles are utterly destroyed." That is, neither all the Nephites have been, nor all the gentiles will be "utterly destroyed."
Well, this is happy news indeed. Some tiny fragment of the gentiles will actually survive the destruction of the coming days! So we ought to rejoice! All is well with us after all! And coming from Nephi we know that we have a promise from one holding sealing authority who will, as I have previously pointed out, seal this prophecy. (2 Nephi 33: 13-15.)
Interestingly Nephi warns his own descendants about their pride and haughtiness. He says that these Nephite descendants, heirs of the covenant, should not think of themselves as righteous. "I, Nephi, would not suffer that ye should suppose that ye are more righteous than the Gentiles shall be." Nephi's prophecy is clear to him, and clear to his descendants. They both regarded the gentiles with pessimism. They (we) are doomed. So they saw us as something dreadful to be compared to. When Nephi confirms they ought not think themselves better than us, he is giving a strong warning indeed. The odd thing is that we read these same records, this same prophecy, and we think we're better than them! We have inverted the picture! We're good, they were bad! But Nephi is using us as the dreadful comparison, the stark warning, the terrible warning that if the Nephites do not repent they will be like us and perish.
When you pick these words apart and see the message it makes you wonder how we could have come to our inverted view. Arrogance and pride really do blind us. Almost completely. What more could Nephi have said to get us to understand? (2 Nephi 32: 8.)