This was WABC, 6 million listeners, but this happened to all the major AM stations around this time in Canada and the USA. Chum 1050 in Toronto was the flagship station in Canada in the 60s/70s. This was Canada's WABC. Chum had half the country's population listening.
Chum 1050 Toronto signing off admitting that advertisers don't want boomers.
https://www.thestar.com/entertainment/chums-rock-n-roll-shuffles-off-dial/article_1d2a8e7d-a08d-54ff-bc16-6143fd87da6b.html
To be candid, they don't want them probably because they're not listening to radio, or media the same way anymore. Marketing for eight decades revolved around Boomer generational buying. Started with their parents buying Matel toys and board games, then the "college" push, and ends with Boomers themselves buying Harley's, investments and now funeral plans. "Rock n Roll" broadcast radio and TV popularity peaked some time ago, probably by the 1990's when all the FM rock stations had finally sold out to big business. There is a reason you don't see "bands" anymore, but just big name acts with a single name. There isn't any growth for profit in any of this.
Radio and TV was a bigger deal for Boomers, and Hearst publications and print were a bigger manipulator for my parents generation.
AM radio as we know is where popular music got its start and migrated to FM because it sounded better. And it did. AM is now almost dead, and FM is either around the corner with death calling, or it will be repurposed somehow. Air waves will be reallocated. Anything internet/cell phone is growth, and the younger generations are glued to it. So, yeah, WABC is gone.
@centinel And that's what got me into this hobby. I am not concerned with advertisers.
Radio abandoned me so I do it myself, for myself, and for any that listen.
As for AM being "dead" in the USA it's the place where most of us do our hobby. You can cover more ground. The only reason I am on FM and not AM in Canada is more chance of listeners, more range than FCC, and there's the broadcasting/nonbroadcasting issue that has been talked about here as the Procaster isn't considered a "broadcast" transmitter in Canada.
But like TV there will always be over the air. If what you say happens and the bands are reallocated it would be the end of our hobby. Why do I need a phone with an app I have to pay for? I can have what I grew up with, a radio and me the programmer. Over the air as it always was. And no app will have what Artisan and I play. This is for newer generations not "us" , or me at least.