Yeah, a lot of radio companies are finding the medium non-viable.
With King's millions, one would think he would keep at least one of the stations on the air, and maybe get on the air himself. After all, he owns them.
Delilah, the well-known night time radio personality, has done that with KDUN Reedsport, OR (1030 kHz), the first station she was ever one. She doesn't expect to make money off it, but wants to serve the community that helped her become what she is today. She still believes in the viability of the radio medium.
Not everyone does, though. And obviously, Stephen King is one of those people who doesn't believe in it.
To be honest, with advertising rates and revenues declining, especially for legacy media like radio, it does put radio station owners in a tough spot. It's a tough business these days.