CC did the same thing in Milwaukee a few years back. Oldies 95.7 was doing fairly well, but they wanted to add more 80s music. So, the station eventually became My 95.7, with mostly 70s-80s music. Ratings were so-so. Finally, a few years later, they realized that the listeners just wanted to hear oldies. So, it became Oldies 95.7 once again, with mostly 60s-70s music, and they shot to near the top of the ratings.
I know everybody wants to add more recent stuff and lower their age demographics, but does it really make sense when everybody's whacking the same pie into tiny pieces? Besides, quite a few younger people enjoy the 60s-70s stuff.