Retail isn't coming back like it was. Downtowns in the past centered almost entirely around retail businesses. The author spends a lot of time bemoaning Walmart and other big box stores, but even the box stores themselves are facing more pressure than ever from Amazon. A small retail store in a run-down third rate city doesn't stand a chance at success against the economies of scale and expectations of consumers that exist today. If a town can draw in boutique retail and bars and restaurants, it can sometimes be revitalized to an extent, but that seems to be the extent of what's possible with old downtowns.
I read a story in the last couple of years about small towns that shot themselves in the foot by keeping out the big box stores - I wish I could find it again. The theory was that the traditional small downtown couldn't meet 100% of everybody's needs, so they started shopping at places like Amazon. And once you start shopping at Amazon, it just becomes convenient to do more and more of your shopping there. Suddenly instead of your downtown being killed by the big boxes a mile out of town, they're being killed by someone much bigger and farther away and harder to fight back against.
I live in the country near a couple of small cities about an hour outside of a major city. The small cities are probably best described as "hanging on." I basically frequent businesses that aren't food oriented once in a blue moon--and never walk around the downtowns. I do shop in the city limits but it's mostly either a supermarket or the Walmart. The travel agency downtown sure isn't going to pull in a lot of traffic.