The iPod is the most popular mp3 player on the market. If you sell digital music, you probably want to include this as a potential device. The iPod plays DRM iTunes music and DRM-free mp3s. Only iTunes sells music with their DRM. If a music company doesn’t like iTunes they have two choices, DRM-free music or exclude the iPod as a potential market.
Is this how DRM “dies”, companies lock-in schemes conflict to such a degree that a non lock-in scheme is preferable? Of course, this is all predicated on the facts above. If iPod did not have the major market share, Apple was willing to license iTunes DRM, or music companies were willing to exclude the iPod from the market this equation changes and room for DRM may appear again.