The buggy whip industry died (and is used as a common example because it died) as a result of something better that completely and utterly replaced the horse drawn carriage. Unfortunately, its a bad example to use because often, especially in debates here on Slashdot, the industry being compared has not been replaced either in whole or in part.
New technology almost never wipes out the old. We still have horse carriages in downtown Montreal. There are still practical reasons to ride a horse: we have cops that do.
We will still have old school mail as well as old school radio in 20 years. It won't go away. It just becomes less economically important.