One place I think Anderson is right is that Amtrak would be better-served by ramping up frequencies on various city pairs/routes to achieve economies of scale (e.g. a station that has to hire two agents to cover a clumsily-timed pair of trains might still only need two agents with 4-5 trains per day in each direction, while it seems quite plausible that running more trains would make Amtrak into a more important "customer" of the host railroads and thus able to get better treatment).
I also firmly agree with this. Railroads are an economies-of-scale business.
I'd personally start with a combination of the Michigan Corridor and Empire Corridor. There's extra trackbed space in all the sections controlled by freight railroads. Buy whatever empty trackbeds you need to buy to have passenger-priority tracks where needed (CSX and NS will both sell if politically pressured enough), and run many trains per day, on time. Chicago-NY via Lots Of Cities is an eminently reasonable route.
I think the main disagreement I'd express is that I put the threshold for reasonable route lengths rather higher than he does.
I think there is no actual limit to "reasonable route lengths". There may be a practical limit to "length of trip for major markets", but the route can be longer than that. The can't-fly-won't-fly market will of course take arbitrarily long trips if they're faster than driving (and it's significant, 10% of the population).
But beyond that, if your major markets are actually Chicago-Denver and Denver-Grand Junction, there's every reason to run a single route all the way from Chicago to Grand Junction -- and that sort of situation happens frequently.
What's important on a train route, IMHO, is that you keep hitting decent intermediate stops every hour or less. So a train travelling across a giant vacant area like San Antonio to El Paso is a *problem*. But if you're hopping from midsized city to midsized city to midsized city, each an hour or less apart, the route could be arbitrarily long. It's good if you can construct convenient overnight service for the city pairs where it's about 8-12 hours, and good daytime service for the city pairs where it's 1-8 hours; you can serve a lot of pairs on one route. Most people aren't riding end to end, of course. The only practical limits to route length come from the problems with dispatcher handoffs and "cascading delays".
Similar examples abound in New York State, where Delta will not sell a ticket from YUL or SYR to ALB. BTW, lest anyone accuse the rules of being rational, they will sell a YYZ-ALB ticket routing via LGA and DTW, something which basically takes those routing limits out back and beats them to death with a shovel.
Air is fundamentally a bad technology for short hops, as everyone agrees. The time penalty of going to the airport, dealing with security, taking off, landing, going from the airport, eats up any advantage (unless you have a private plane or something). For short hops, it's driving, buses, or trains. But it's not just the short hops where airlines can't provide economic service, while trains can...
Airline service has become one of strictly point-to-point flights -- air routes don't have multiple stops any more. (Because of the huge costs of takeoff and landing, both in time and fuel, and of boarding/deboarding in terms of time.) This renders air travel uneconomic for lots of city pairs.
While a train can hit Albany, Utica, Syracuse, Rochester, Buffalo in one run, that would require a minimum of 10 airline flights just to serve each pair. The traffic demand isn't there for that, so those flights don't exist. (Actually, I'm not sure there are flights between *any* pair of those cities.) Sure, between the very biggest hubs like LA, SF, Chicago, and NYC, every pair is served by air, but as soon as you get to smaller cities, they're not.
As a result of not having intermediate stops, airline service has become a strictly hub-and-spoke affair. Puddlejumpers serving smaller cities generally go only one direction, to the nearest hub. Then the hubs are connected. The hub-and-spoke routings mean that airlines are uncompetitive for many of the city pairs which trains can serve very easily by stopping at a chain of cities.
Another interesting example is going from anywhere in Vermont or Western Massachusetts to Albany or points west -- the planes only go east to Boston.
The disappearance of point-to-point routes, unless you're going from a hub to a hub, or a small city to *the one hub* which it is connected to, means that air ends up being much slower than driving for the routes which air has "abandoned" due to indirection, even if you can technically glue together a route (for instance, by air you can go Ithaca-Detroit-Boston-Lebanon NH -- no, just no).
Trains can compete with driving. When air travel is slower than driving, trains can also compete with air travel.
Serving the can't-fly-won't-fly market (10% of the population, roughly) is a bonus. Many of them drive, so again the key competition is driving.
"Airline thinking" is no good for a railroad. For an airline, all flights are point-to-point; for a train route, it is essential to have numerous intermediate stops to leverage economies of scale. (Auto Train notwithstanding.)
In response to adamj023, I will simply say that NY-LA is the wrong example; sure, those are big enough to have lots of direct air flights. You want to be looking at Syracuse to Milwaukee, and the many many other city pairs like that.