"Clear Channel started up FM talk stations in the Twin Cities, Pittsburgh and Madison because they had no substantial AM stations to do it with. WPGB in Pittsburgh has been doing well, but not as good as the 800 lb.
gorilla, KDKA."
However, WPGB is stealing enough listeners from KDKA that its "brother" station (as they refer to it on the air) WDVE is now #1. Clear Channel could have very easily switched their AM property, WWSW from sports talk to news/talk, but they decided to convert 104.7 FM because that station was doing extremely poorly, and had been doing poorly with a wide range of music formats. I don't know what Clear Channel does in other cities, but here in Pittsburgh their strategy is to "protect the Mothership" (WDVE). Everything they do with their other stations is filtered through a "how will this affect WDVE filter?".
And, though it is taking time, KDKA is slipping, and slipping badly. Their audience was already extremely old, now it's getting ancient. They lost Rush Limbaugh to WPGB, and now they've lost the Pirates to WPGB as well.
One thing I don't think is a significant trend is the moving of news/talk stations to FM. It will happen, but not as any sort of a master strategic plan. If an owner of a cluster of stations has an underperforming FM available, then they might switch it to news/talk. I don't think you'll see many cluster owners with a news/talker on the AM band move that programming to the FM band just for the sake of doing it.