How ephemeral does something have to be to be ephemeral? I think of mayflies (which only live one day), but maybe I am just destroyed by my knowledge of Classical Greek and that ἡμέρα means 'day'. Can you call a technology like the CD that only lasted for a few decades ephemeral?
ephermeral TFD I would not at this point in time call it such.
lasting for only a short time; transitory; short-lived: ephemeral pleasure.
Ephemeral was originally a medical term with the specific meaning "lasting only one day," as a fever or sickness (Hemera means "day" in Greek.) The dominance of the the CD format lasted from ~1980 to about ~2008. One's childhood has been so labeled. Context is important. I suspect in a century the CD format will be called such.