The Library of Congress did a study of archival audio storage in the 1980s. In this study they concluded that laminated media like tape and CDs had lifespans that were measured in years and a couple of decades, depending on storage.
Ralph, The CD is about to turn 40 next year and so far there have been very few reports of CDs failing. I know that I have CDs from the 80s that still look and play just fine. So I think we can scrap that LOC study.