It is far too early to write off recorded music. File sharing and internet presence has been the greatest thing to happen to the music industry in decades as it has provided an alternative to the major recording companies and Clear Channel's attempt to control what music listener's are allowed to hear. If one follows the logic of labeling a file sharer as a thief, then everyone who has copied a TV show or movie on a VHS tape, or 'horrors' on a DVD is a thief as is everyone who has checked a book out of a library or read a magazine in a doctor's office, or copied the words of a song from the radio or recording. All have used a "commodity" without paying the copyright owner their just due. The only real difference is that the recording industry has the resources to buy the law. As for downloading of music hurting recording sales there are far more reasons why sales are diminishing than file sharing. Other businesses that have seen sales decline have blamed the economy. Only music blames internet users. The music industry says nothing about the dramatic rise in DVD sales. They certainly don't blame an overpriced product, but the industry was doing well with cassettes selling for $9.98. CDs which cost less to produce than cassettes have continued to be marked near $17.00

Here is a New Scientist article on the subject.
New Scientist

Here is the original paper.
Original Paper