Where did all the song traders go?

According to recent Pew Internet Project survey, the number illegal song downloaders has plummeted since the RIAA began filing lawsuits against individuals it suspects of illicit sharing large quantities of illegally copied music. According to the survey:

A new nationwide phone survey of 1,358 Internet users from November 18-December 14 by the Pew Internet & American Life Project showed that the percentage of music file downloaders had fallen to 14% (about 18 million users) from 29% (about 35 million) when the Project last reported on downloading from a survey conducted during March 12-19 and April 29-May 20. On an average day during the spring survey, 4% of Internet users said they downloaded files. In the November-December survey just 1% said they were downloading files on any given day during the survey period.

So where are these people going? New, legal download sites such as iTunes? Or are they headed further underground, as suggested by GMSV's John Paczkowski, to services such as BitTorrent? The Pew survey does not seem to take into account these "alternative" download options. My guess is that it's a combination of both the new legal and harder-to-find illegal services. ITunes and the like make it relatively easy to find and download a song and its cheap: Anyone can rationalize a buck. BitTorrent, which is more cumbersome to use than Kazaa, is also pulling in its share of users. The RIAA legal action is probably a smaller-than-touted reason for the decline in a illegal song swapping.