I disagree, sure it maybe impractical but we don't know that for sure until we really test it out.
Here's an excerpt from wikipedia page on drag,
"Power
The power required to overcome the aerodynamic drag is given by: ...
Note that the power needed to push an object through a fluid increases as the cube of the velocity. A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW).[16]
With a doubling of speed the drag (force) quadruples per the formula. Exerting four times the force over a fixed distance produces four times as much work. At twice the speed the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, four times the work done in half the time requires eight times the power."
So in light of that problem, an engineer wondering as to how much better a train would function in a low pressure environment, or
a vacuum, isn't a completely disconnected thought, unlike with the solar roadway project.
And suppose that doubling of the speed came for roughly the same energy expense as a train traveling half that speed through
air at 1atm? That would be getting a level of performance that would normally require 8 times more power!
Now lets use the transrapid as an example, which I am fairly sure is the one you rode if this was in China.
Again wiki states,
"The normal energy consumption of the Transrapid is approximately 50 to 100 kilowatts (67 to 134 hp) per section for levitation and travel, and vehicle control. The drag coefficient of the Transrapid is about 0.26. The aerodynamic drag of the vehicle, which has a frontal cross section of 16 m2 (172 sq ft), requires a power consumption, at 400 km/h (249 mph) or 111 m/s (364 ft/s) cruising speed, given by the following formula ... 3.53MW"
So under the hyperloop concept, assuming the utmost ideal result, you would be getting double the normal performance
at 3.53MW instead of 28.24MW!
That seems worth trying out imo.