If you own an HD capable radio, it already has the ability to receive pure digital AM radio.
There is not much disagreement that hybrid AM did not work. There just is not enough spectrum to support both digital and analog. Combined with the increase in background noise, the whine of the digital signal wipes out adjacent AM signals.
The same type of transition occurred in the 1960s when very few car radios could receive FM signals. With no listeners, there was no reason for creating live programming. With no interesting programming, FM stations were never going to get listeners. Without listeners, there would be no revenue from advertisers, If that was your business model.
FM is a far better technology, and has much more spectrum available to do things like sideband transmissions for reading services for the blind, displaying song titles, traffic data, etc. With HD, each license can support up to four separate programming streams. If FM also went all Digital, HD technology supports up to seven programming streams per license. If every FM station add seven separate streams, radio would become the same junk land that cable TV has become. You have 652 cable channels but nothing worth watching.
ALL Digital AM will require a lot less power and sound more like stereo FM for music quality. In theory, digital AM could support a second programming stream, But the FCC is not convinced it is technically feasible.
Switching to all digital AM will break existing non-HD radios. Expect that people still listening to radio on their portable radios from the 1960s or their vintage tune radios from the 1930s will scream bloody murder. A large portion of AM stations already have FM digital translators, so the solution is you can listen on FM. This is how we might save AM. This transition is voluntary. For now.
All FCC commissioners forward to support this rule change. People opposed to the transition to digital TV on similar notions, but I think most people now recognize that it was important to do