What makes a station relevant. If it serves some niche of folks who listen and the station owners make enough profit to be happy, then from where I sit, that radio station is relevant, even if it's a 250w station.
We've lost a number of stations in the Delaware Valley as the years have passed, that may not be missed by many folks, but to those who's lives were made better through the entertainment, information, and radio personalities who's voice and style was like a visit from an old friend via these small time stations it is a big loss. Many here lament the loss of the Ken Garland era of WIP with that entire stable of Metromedia air talent and music, jingles, promotions, cash call, Chickenman, etc, that made that station one of the best in the nation bar none. Yet to those too young to have been there to experience that 610 WIP, its not relevant. Or what of the Boss jocks at Famous 56 WFIL before it became Salem Radio's Christian Talk Station, or the great real radio talk shows on WCAU radio 121 in Philadelphia, WWDB The TALK STATION. Those of us who like Classical Music still miss WFLN at one time AM and FM, now there's neither. Thankfully Temple's WRTI decided to go half and half Classical and Jazz. But the point is, Time marches on, what's cool and hip today will be passe and old fashioned tomorrow. Yet for those who's lives were touched by what a WHAT, WCHE, WAMS, WNRK, WTUX, WNNN-FM, WJIC, (and many others whose calls I don't remember, because I couldn't get them on my radio) that are no longer with us, those stations were relevant to someone, even if they weren't the biggest or best profit producers in the tri-state area, they served some group of listeners and advertisers. So if WHAT has gone silent and has now joined that club of former radio stations, it is a sad thing for those who spent many years working there and for those who spent many years listening to that station. It's not the end of the world (only Harold Camping thinks he knows the date God has chosen), but it still is a loss for Philly area radio listeners.
Granted some of the stations I've listed have something being aired at that frequency with different calls, different owners, different programming, but it's not what those stations were in THEIR hay day. However, even these newer versions are relevant if they are serving a group of listeners, advertisers, and making enough of a profit for their respective owners. People are creative and have found many ways to reinvent AM radio, some 90 years later.