I assume the majority of families live in the suburbs so putting a true AC station (i.e., Sunny 99.1 in Houston) up north could make sense for 105.3 or 105.7/. Probably an AC station right in the city wouldn't attract much due to demographics. And now that Fish is gone, someone is going to have to fill that Christmas music-void. And don't call the station, "Peach" - sounds too cheesy lol.
105.3 is a southern, not northern, signal. 105.7 is a very limited signal that covers basically the northern part of the market. It would not be able to compete for the ratings needed to attract buys with a mass appeal format. What 105.7 is doing now is the best use of that signal. It puts a strong signal into the heavily Hispanic areas of the market.