I may regret this, but I am going to wade in here on the issue pertaining to the future viability of AM. Basically, every move that the FCC has permitted since about 1986 has conspired to smother this platform. Breaking up the clear channels was the first big nail in the coffin. Why? Not because it ruins the experience for us dxers - but because it tries to deny the science of MW radio transmissions. They bounce at night and, sometimes, during the daytime too. In doing so, they can interfere with other signals that are close by in frequency. And, this happens over a range of hundreds of miles. Yes, I know that all of us here get that. But, the FCC doesn't seem to.
Why do I make such a seemingly absurd comment? Because the FCC has pushed localism over all else on AM for 20+ years now. Earlier iterations of that bureaucracy got it - but these guys are more interested in representing the supposed interests of station owners (big ones, really) over all else. In doing so, they've shoehorned stations into frequencies and geographical carve-outs where they never belonged. They permitted daytime-only stations to operate at night, even though the original license was issued with more wisdom than that. And, more recently, they permitted AM IBOC transmissions.
Each of these things has contributed, point by point, to a degradation of the AM listening experience. Go back to the 1960s and you could listen to AM on a wide-band radio, which sounded pretty good. You didn't have all of the interference. And, yes, you could listen to the clears for most of the night with only minimal fading in many cases. IF the AM band still had proper spacing, maybe AM IBOC could be made to work. Trouble is, there are probably 3 times more stations on the band in the USA than should be allowed there.
If you want to make IBOC work on AM, you would need to revoke licenses from most of the little guys. Because the band is too damn crowded on AM in analogue and there's no real space to steal the sidebands for IBOC. Yes, I know, market by market I would seem to be wrong. But, AM signals don't neatly stay in one market over another in the way that FM and TV stations usually do (though there are some big exceptions to this too). Once you turn the noise generator on, the analog signal sounds even thinner - further contributing to poor sound quality on AM. As you can see, every move made in this band in the past 20-30 years has been technically foolish and each has contributed to the slow death of AM.
You know, there are AM stations that still get great ratings. With great content and a solid signal, people still listen. But, all of the above issues contribute to AM's bad rap among younger demos. And, forget the ethnic newcomers - by and large, they already hate AM and most never listened in their home countries. That too is because of poor sound/signal quality AND poor content. Most latinos, for example, would never tune to AM. Which is ironic, because so many AM stations try to program ethnic formats. But, most seem to draw only small audiences. The successful Spanish stations are on FM, not AM.
I'm of the opinion that the AM band can be saved by thinning out the herd (pulling in licenses) and by recognizing the reality that AM signals bounce when the sun is set (or low). Any technical changes to signal quality must take this concept into account to be viable. AM IBOC does not seem to recognize this reality, which is why it should be scrapped OR the band realigned to make space for it. One or the other. If AM is allowed to continue along this path, it will die because it sounds like crap. Too much interference between stations, making it too hard to listen to in many cases.