This article says that they are.  More importantly, it says that people do not care as much about their music or the quality of their music-listening experience as much as they once did.  That's very interesting if true.  I wonder if this is a permanent trend or if it is temporary.  Beyond a certain point, the average person definitely does not care about the quality of their sound.  How else can we explain the explosive growth of low-bitrate MP3s?  They are moving to higher bitrates now, but when the Diamond Rio had 32 megs of RAM, people weren't listening to 192kbps tracks.  The list of high-quality audio formats built to replace the CD is long.  The list of failed products is equally long.  DVD-Audio?  SACD?  DCC?  DTS CDs?  None made more than a blip on the radar.

Of course, quality audio for music may be declining, but people are paying more attention to the audio in their home theaters now.