Sorry, but i think that is ridiculous. In the riots in the major...

Sorry, but i think that is ridiculous. In the riots in the major cities Chinese establishments suffered damage. The obvious answer is the Vietnamese or the Chinese or both would close the Border and Visas would not be issued and as 90% + patronage is Chinese you have a problem.
This is the worst case scenario. If it happened it would be a day, a week, a month. Vietnam needs trade and an honourable outcome in the South China Sea. I think a Trade Off might be in order. The Chinese are hard nosed but World opinion is beginning to be of some consequence to them.
RAB