I doubt Bungie will address this directly, but I don't think so. Clearly some similar themes are being explored, and Bungie may very well be giving a tip of the hat to old school fans with this reference. However, the Cortana in the Cortana Letters is still quite clearly a different character from the Cortana we know in the shipping Halo games, and it seems doubtful to me that further analysis of the Cortana Letters, as entertaining as it is, will prove useful or relevant to the events of Halo 3.