Everyone raises good points, but one factor absent from the conversation has been WBOS. WBOS is actively trying to rip the male LoHaS psychographic away from WFNX. Given that introduction of rivalry into the competitive system, it makes sense to invest in the core asset that generates value for the listener. Eliminating commercials to improve TSL is certainly a valid, albeit costly, approach to do so.
But how does 40(50?)-something Julie Kramer do something that a 20-something female DJ cannot? Perhaps this brand reinvestment would be wiser if executed with new talent, a new star for the next 20 years. All investing in Julie Kramer does is make WFNX skew older and older. But if you cut her loose she can go to Radio929, and theoretically bring along the listener relationships she had at WFNX. But that is a good thing, because it will bring along older women, a group unaligned with 929's target, it will be outside their core business and they won't immediately know how to sell it. Furthermore, the smarmy delivery will certainly turn off the Ya-Dudes, alienating their core.
Parting ways with Julie Kramer makes WFNX better positioned for the Millenial generation that will drive the stations sustainability in the future, with the added benefit of really throwing a spanner in the works of WBOS were WBOS to pick up Julie Kramer (which I believe it would, in fact were that the case I would expect to see WBOS return to its "cool over 30" audience targeting that made is $$$).