Interesting article indeed. My take is that it's mostly promotion by folks who already believe in digital and want everyone else to buy into it.
And notice that there wasn't a single mention of adjacent channel interference caused by digital signals..! But I suppose that's already well documented.
Nothing is going to "revitalize" AM radio until or unless owners are willing to cough up some bucks and put on programming that listeners
WANT to listen to, rather than what's going to make the station the most money for the least investment.
America needs a sense of humor...