Redactive analysis: Nephi is quite conscious that his writings are specifically for an audience. At times it appears that it is exclusively a future audience, but phrases like this one appear to give him a more immediate purpose. It is certain that his words are affecting millions of we who are in Nephi's future, but it is not certain that we would easily fit into Nephi's category of "unto my people."
Because this statement appears in Nephi's justification of his record (following his description of the command to write this particular set of plates 1 Nephi 19:1-4) it is probable that he is writing of his immediate people, and his heart is currently turned toward them. That his descendants appear to have forgotten these words is irony available to we as his future readers, but not available to the intents of his heart at the time. When writing these words, Nephi wrote them for his people. The delivery of the import of those words may or may not have been through the medium of the small plates, but it is certain that he would have communicated that information orally.