ratings are down and we need something new to attract an audience. She states "Were the ratings sinking, perhaps? They were not. Morning Edition's audience grew by 41 percent in the last five years; Edwards' is the most-listened-to morning radio program in the United States." but numerous programs lay claim to that title. Grew by 41% is rather meaningless by itself too and no base audience was given--a base audience of 1000 or even 10,000 increased by 41% still isn't much of an audience.
This is all just HER INTERPRETATION of an event and absolutely nothing indicates her interpretation is even close to correct. He is not being "let go" as would be most likely if age were indeed the factor--he is being made a senior correspondent for NPR which is an unlikely position for one considered a "has been".