I call total BS. There is no way that this NPD firm can "track deletions." IMO, what they are calling "deletions" are just people moving their music files out of their Kazaa shared folder (or ceasing to use Kazaa at all).
Sometimes when I am reading "the news," I often wonder if I am actually reading "news" or some special interest's propaganda. In this case, there is no question. That article was pure propaganda ala Orwell.
A related NPD survey of consumer perception, however, found that consumers' overall opinion of the recording industry is suffering due to the RIAA's move to sue hundreds of people alleged to have illegally shared music online.
And in related news, scientists discover that the sun rises in the east every morning and sets in the west every evening...