There were (not only) Lamanites

See the linked story in the SL Tribune here.

If you have not heard about it yet, the Church changed a couple of words in a sentence in the Introduction to the Book of Mormon. Where the Lamanites were once the "principal ancestors" of the American Indians, they are now only "among" those ancestors. Interestingly, this change has initially been buried in the Doubleday version of the BOM (the commercial one) instead of the Church's official one, though the change will be incorporated there soon, according to the article. Further, I just checked the on-line scriptures at LDS.org and no change has been made there. And the change has not been mentioned or explained on the Church's website (which seems to carry just about everything else going on in or around the Church these days)

I admit that I have a very cursory understanding of the DNA issues regarding the BOM and an even smaller understanding of alleged textual changes in the BOM over the years. But it seems to me like a change of this kind is significant. What kind of approval process does this have to go through, I wonder? Of course, this is only the Introduction, which was written by BRM for the latest edition of the LDS scriptures, published in 1981, so it isn't like they are changing the translated text of the BOM.
Does this mean that the Church is accepting the "limited geography" hypothesis about BOM geography as well? As I said before, I am not well-versed in the DNA issues, but was the "principal ancestors" model no longer defensible based on the evidence against it? For those who may have a little more knowledge on the subject, I would love to learn more.