Yes, some of those tapes fade over time, but I am still listening to tapes from the 50s and 60s that are great. I have been buying a number of old tapes on Ebay, and they sound excellent. One problem is that occasionally they will break. For instance, the movie soundtrack to "West Side Story" has fabulous sound, but at least two have broken on me. If they are music you might like, keep them. Furthermore, a Tandberg in good working condition can bring nice dollars on both Audiogon and Ebay.
Jim
Jim