As far as I know, KKGO has never cracked the top 20 in 25-54 through its nearly thirteen years of existence unlike other country stations which have enjoyed cume numbers in excess of 1,000,000, with KPLX/Dallas & KILT/Houston, so I assume their 25-54 numbers have been solid for many years as heritage country stations.
KKGO is consistently somewhere between about 12th and 18th in 25-54. Considering that the differences in AQH persons in that mid-range of ratings is fairly small, just a sampling error can change a station by four or five rank positions.
It has been in that range for a decade, with little change despite the "white flight" from LA County and southern California in general.
He went on to say that in Los Angeles, stations that cater to mostly white listeners are 'playing for less than 25% of the marketplace on a good day'.
That is correct. 75% of the market is ethnic and first generation immigrants, few of whom listen to country.
Is there any reason not to expect that KKGO will continue to struggle in attracting listeners in the 18-49 and 25-54 demos as KZLA did back then?
It's not struggling. It's a very successful station with billing around 120th out of 15,000 US radio stations. No debt, family owned, a real money maker.