For some reason, programers missed the fact that the "oldies" format was never meant to be static. It was never intended to hit a year-wall, like 1972, and never move beyond it. It was always intended to drop a year at the older edge and add a year at the newer end. In the 80's, like 1985, you might still be playing 1956-1972. Then in 1986, you would start at 1957 and extend through 1973. And on it would go.
The trick is picking songs from the 80's that blend with songs from the 60's. CBS-FM is doing it right. It's the only way to save the format.