Like I said before, they'll never stop trying to leave, they just won't succeed. Ask yourself this, has the Vietnamese public and foreign policy attitude toward China done anything substantial recently? Anything at all? It went from full-scale conflict in '79 to sea skirmishes in the subsequent decades to now mostly just rhetoric.
I recall a saying by a top Vietnamese official from many years ago, it went something like the French come and go, the Americans come and go, but China will always be here. Take a look from their perspective, they're living under the ever present threat of being swallowed up by China, if not militarily at least economically, culturally, and politically. They'll never stop trying to stop this, as they know what happened to the kingdoms of e.g. Dali or Manchuria, kingdoms that once were but never will be except in Chinese history books.
Don't expect them to love China so easily, because the moment they do is the moment they've lost--their country, their culture, and their identity.
Oh no, Vietnam is stuck with China for better or worse, but that does not mean they won't cause China any damage if they really want to, they are the only real resistance left for China in Asia Pacific now that Philippine has folded. US carrier is going to dock in Vietnam next year, and Vietnam is probably going to start to buy US weapons and with any chance another US base right on China's footstep.
Does this going to effect China in the long term? not really, does it going to have a impact on China in the short term, very much so.
It seems your argument is that its in Vietnam's DNA to hate China, and also in Vietnam's DNA to submit to Chinese dominance therefore China should not worry about Vietnam, because eventually history will win out and China will have its way... to be fair yeah that is the historical pattern of interaction of Vietnam and China. But still, in the modern age, do not underestimate a unified nation of 90+ million under China's noses and being very hostile to China, they are capable of doing real damage to Chinese interest if push come to shove. Therefore Vietnam's action towards China does matter a lot more than you like to easily dismiss, and for same reason, a unified Korean with similar sentiment towards China will be the same.
And lastly it seems everyone think I'm being an A-hole for preventing Korean from unification therefore from a morality point of view I'm wrong. No, not really, Vietnam would NEVER unify without China's help, China send tens of thousands of Chinese into Vietnam to fight for them, run logistics for them, giving them food, weapons, ammo, setting up SAM network etc... And that was during the hardest time of China's great leap forwards, millions of Chinese were dying of hunger, but Mao collected rice from starving farmers and send it to North Vietnam so they can free up the Vietnamese farmers to fight in the South, that was one of the most stupidest action China have ever taken, if China had done less or nothing, Vietnam would still be divided and busy feuding with each other, and China would not suffer such sacrifice. Same situation for Korea, the only way for Korea to unify is for China to get involved to help one side over the other, there is no way in hell both Korea will unify with each other on their own, therefore if China decides to do nothing its not morally wrong, this is what I'm advocating, do nothing and Korea will stay divided until a much more powerful China arrives in the future to better deal with Vietnam and Korea and Mongolia and Japan.
