As cool as it'd be, my inner cynic is not pleased. First of all, as China operates on a combination of Standard and 1200mm gauges, plus (probably) on Russia's 5' something or other gauge, the train must have multiple locomotive and wagon changes/very good variable gauge bogies.
Also, the multiple safety systems employed by each of the countries it passes through must be included otherwise it'll be unable to go anywhere at all.
Another factor is the ever-lowering cost of air freight. With the hiring of the Antonov AN225, it becomes much easier to move large and unwieldy consignments across the world at a fraction of the cost.
Constructing and prototyping a train which must comply to these strict parameters will be nigh-on impossible, if not prohibitively expensive.