[mgkuhn]

What exactly does he technically want to preserve? Does he really care about amplitude modulation? Or does he care about the frequency band (medium wave, HF) and its propagation properties? Or does he care bout the geographic reach of these stations?

Amplitude modulation is a historically important technology, because it was technically very simple to receive in the early history of radio, and because it was more bandwidth-efficient than FM. But it remains utterly badly suited for mobile reception, because it is highly sensitive for multi-path interference (unlike FM).

We have now far better modern, digital modulation schemes, including DAB and DVB-T2 for VHF and DRM for long, medium, and short-wave transmission. They provide (thanks to OFDM) much better audio quality and interference resistance than the old analogue modulation schemes, and they are also far more power efficient, which substantially reduces the enormous electricity bills of the transmitter stations. They also are very bandwidth efficient, and can be used in single-frequency networks.

[jejones3141]

Agreed about digital modulation, but I recall hearing multipath a lot more on FM, or perhaps it was just more obnoxious there. Traveling around large buildings or under a metal bridge would bring that familiar rapid flutter as the car moved through places where the reflections would reinforce and cancel. (You can drive through a lot more wavelengths per unit time for FM than AM.)