That’s several thousand miles of additional journey on your way to Shenzen or wherever? Massive amounts of track, tunnel and bridge that has to be maintained in extreme conditions and across multiple nations at odds with each other?
I don't think it would be as problematic as you suggest. The Trans-Siberian railway already operates at similar distances. Also China is building their belt-and-road network. We could get goods from China, Japan, Korea and Russia all on this rail system.
The one sticky point might be gauge. We'd want something all agree upon. We'd want to avoid variable track gauge bogies.
Or just put it on a boat?