In response to posted news (shared on Facebook's I Love AM Radio group) that KIDD-AM 630 and KNRY-AM, both in Monterey, CA, were donated by radio legend Saul Levine to a religious broadcasting group, I said,

When AM radio finally dies (not a knock: all things do), its last living cells will be religious broadcasters (also not a knock: just an observation).

To which another person there replied,

Doc, there will be more than just religious broadcasters. Here in SoCal there's Spanish (a lot), Chinese (on a 77kw Mexican signal), Sports (3 from L.A., 1 in San Diego now), a couple of music stations (one is playing "Adult Hits" out of Texas on a 50k signal) - There's Middle Eastern radio, and more. The trouble here is in the numbers. Can you imagine how it would be if there were 10+ stations playing the same music? That's kinda like how it is here. What we used to call "broadcasting" on AM is turning into "narrowcasting" - driving more and more people away. There are at least 15 ethnic stations, 2 News-Talkers and one all news station covering more than 15 million people. Not a knock either. It's reality..a sad reality!

And to that I replied,

Here in Santa Barbara, with a salt water path bringing coastal AMs (all the way to Rosarita, NL) in like locals (and tropo doing the same for FMs much of the time), it's clear that both bands, in different ways, are turning into narrowcasts: religion, ethnic groups, sports, partisan political talk. The list goes on. The one conditional exception is public radio, which tries hard to hold a political center it can't have because, except for the local stuff, it's based in Washington, where policy, governance and academic specialties are the lenses through which everything in the world appears.

I think the reason SiriusXM succeeds is that it offers a much wider range of channels programming on its "dial" than anything anywhere in terrestrial radio. It also has the good fortune to have stayed alive and thriving in an economy that is moving economically from a free basis to a subscription one.

What SiriusXM can't (or doesn't) offer yet is what will keep terrestrial radio alive: exactly what you're talking about—ethnic,sports and other forms of narrowcasting.

The big challenge for all of it will be getting future devices to hunt from one "band" to another: over-the-air, satellite and streaming over the Internet. This is do-able, but in the long run only if the whole combined system is digital.

This is why I have some hope for full-digital AM radio. The open question is whether the gear-makers (especially for cars) will be willing to do the work. I suspect they won't, especially if the transmission and reception ends require costly proprietary encoding and decoding, and just one source of parts. This, more than anything else, is what's killing HD Radio. (Forget the actual engineering details. What matters is that HD Radio is a market captive to Ibiquity. Unless I have that wrong. And tell me if I do.)

Just thought I'd share that. If the thread grows, I'll add to it here.