As they naturally would. "true classic rock" ended sometimes in the mid-80s. The people that aren't interested in music any newer than that are all at least 60 by now.Many former "classic rock" stations are now switching to "classic hits"; apparently the successor of the oldies format. They're playing music from the 80's on. Ft. Lauderdale's WBGG )Big 105.9) made this switch, leaving the market without a true classic rock station. Thank goodness for SiriusXM.
When I was a kid, there were radio stations that played only stuff from the pre-rock era. Those formats don't exist anymore.
Why do you think that is?