Russia already has trans-Siberian rail and well developed, China don't want to spend more money for nothing, rather China is developing other alternative roads such:
Kashgar-Central Asia-Turkey-Europe
Kashgar-Afghanistan-Iran-Turkey-Eurpe:
Kashgar-Pakistan-Iran-Turkey-Europe
Aircraft Carrier is to defense our eastern sea roads
Iran use standard gauge too, I hope the Kashgar-Gwadar rail gauge is standard so we can link eventually to Iran, turkey than Europe, this way we dont need to have cargo transfer. And that will benefit Pakistan also to have direct rail link to middle east.