Image: Train passing through the Chinese/Russian border/Wikimedia
About 30 yards from where I'm writing this is the Northern Transcon, one of two transcontinental routes operated by the BNSF Railway (formerly the Burlington Northern and Santa Fe Railway). Trains pass through at a rate of about two every three hours—up to several an hour occasionally—heading west into Portland, Ore. and east to Chicago and points between. In Spokane, a couple hundred miles to the northeast, the Seattle portion of the Transcon will merge with the Portland section, and it'll continue 1,800 miles or so from there to the rail heart of America, Chicago.
The sheer volume is something to consider: carriages making up a full couple of miles worth of stuff, potentially weighing in at more than 20,000 tons, moving by at 60-plus miles per hour. The startling efficiency statistic is that it takes only a single gallon of fuel to move a single ton of that cargo for about 500 miles. That, in essence, is why railroads will never die; it's because of all of our stuff and how we've rebuilt our civilization such that that stuff can come (and go) from anywhere on Earth in a short amount of time. For better or for worse, rail and its marvelous fuel efficiency is the sole reason that it's possible to export coal and grains fron the United States at all. Oil can travel by pipeline as an alternative, but not dried corn or the fruits of West Virginia mountaintop removal. (Efficiency sounds green, but it also doesn't play favorites like you'd expect.)
The 2,000 miles (roughly) of the Northern Transcon is less than you think. If you want to see the realest argument for rail transport, look to China, the eastern terminus of the new(ish) "Yuxinou" line, spanning 11,000 kilometers from the metropolis of Chongqing to the German city of Duisburg. a 16 day journey (vs three or so on the Transcon). It's a distance that on the one hand seems rather insane for a single rail line, but on the other makes putting goods into trucks or ships look even more insane. It shaves a full 20 days from the alternative sea-based route, which currently sees about 95 percent of traffic between the regions.
That share is quite a bit less than freight rail transport in the United States, which makes up about 30 percent of everything (the rest taken up mostly by trucks). Right now, there are only three weekly trips on the line, making those many thousands of kilometers very, very loney, and the trade deficit between China and Europe right now has trains often running full only one way from Chongqing and relatively empty on the return. In other words, the line has a lot of spare capacity, even mostly spare capacity. But recreating trade routes/mechanisms spanning the largest land mass on the globe won't happen evernight; it has some time to earn its "New Silk Road" nickname before being cast aside as merely the largest steel ribbon on Earth.
The line has actually been around for a decade, collecting rust and weeds, while the intermediate nations agree on customs check rules and sort out 11,000 km logistics. (Worth noting is that the line passes well north of the Ukraine and Crimea.) Trade has become a lot more bureaucratic since the original Silk Road. Until now, with the launch of reasonably frequent weekly service, the line has just seen a single paltry monthly train. One notable future potential client is none other than Foxconn, which has much of its operations based in Chongqing, as does Acer. One might even imagine a future in which the New Silk Road becomes the new silicon road, albeit hopefully with trains piloted by adults.