"We've run out the clock for a non-current music format on a station with the call letters KFRC to have any relevance."
I think you're giving call letters too much importance, Michael. If/when 90s "Classic Hits" or whatever you want to call them - become popular on the radio, there's no reason the station can't still be called KFRC. To use another example: the KMEL call letters started in the late 70s as an AOR station. Then the station flipped to "All Hits," then morphed into Rap and Hip/Hop; yet the call letters have remained. The "brand" has had different meanings in different decades, and nobody in the station's current core audience knows or cares that it used to be an AOR station with a Camel for a logo.
When KFRC flipped to Magic 61, James Gabbert (who appreciated their heritage) offered to buy the call letters from RKO for his fledgling TV station. RKO turned him down, but if we had spent a decade or more watching his "KFRC TV20," they would have a different meaning altogether.