How popular has Nanning-Pingxiang-Hanoi proven to be?

I understand that the distance is under 400 km. Guangzhou-Nanning-Hanoi should be shorter than Guangzhou-Changsha-Wuhan.

Hm. Some numbers:

Population:
Hunan - 65,68 millions
Hubei - 57,24 millions
Guangxi Zhuang autonomous region - 46,03 millions
Vietnam - 90,39 millions

Per capita GDP, 2012:
Hunan - 5304
Hubei - 6111
Guangxi Zhuang autonomous region - 4427
Vietnam - 1528

Total GDP, 2012:
Hunan - 351 milliards
Hubei - 352,5 milliards
Guangxi - 206,4 milliards
Vietnam - 138,1 milliards

Should a high speed railway be built Guangzhou-Nanning-Hanoi, to allow the Vietnamese working in Pearl River delta to go home more often?