I'll repeat what I said when KOIT first topped KGO in the last trend. I think KOIT has gained listeners who have nowhere to go for Oldies/Classic Hits. Think about it - the majority of songs KFRC played - both 60s Oldies, and later 70s-80s classic hits, were more or less on the "light rock" side. Over the last few years, "light" has gotten more mainstream with more upbeat hits, and fewer soft romantic ballads and Celine Dion type glop. (KOIT has even played Springsteen lately). With KFRC gone, people have nowhere to go but KOIT, Kiss-FM and KBLX, and those last two only play "old school" (classic soul). KFOG, and of course, the Bone play a lot of classic rock, but their sound is too hard-rock for a lot of listeners. KOIT's also shares a lot of new music with Alice and Star.
With the addition of more and more talk stations (now KTRB), it seems obvious that KGO will continue to trend down, while KOIT gets even bigger,