I used to live in Tucson in the 80s and worked at KTUC. I now reside in Seattle, and can only share what happened here. KIRO AM, a 50,000 watt powerhouse in the Pacific Northwest, flipped their AM news/talk to FM and everyone thought they'd gone nuts. After only two years the station is #1 in the ratings on their new FM frequency. The AM flipped to all sports (ESPN/local hosts hybrid) and still ranks in the top 10. As to KNST, returning to KCEE, that won't happen. KCEE is on 690 and is owned by Good News Broadcasting. As for putting oldies on 790, unlikely. Clear Channel which owns KNST, just had oldies on 1450 KWFM which they own as well, and it didn't last too long, now the station is all comedy. KSL in Salt Lake City runs their news/talk on AM and FM, and own the market (#1 for many books). KNST will more than likely just pick up a lot more listeners that never bother to check out the AM dial, and continue to hold the ones they have. In areas where the FM signal is clearer, it will give those listeners a better sound (no static, hiss, etc) that is so the bane of the AM dial.