If possible, I would like to have some of these vietnamese ethnic back to Vietnam, just to know more about Hán Nôm.If Vietnam remains in China, soon Vietnamese will become yet another Chinese dialect and disappear.
Kinh and Chinese assimilate each others extremely well. The Hoa think they are Vietnamese and Vietnamese in China think they are Chinese.
But Chinese Kinh almost concentrated in Fangcheng which is few km from Vietnam and they like to marry girls from Vietnam. So they preserve their language till now.
My Chinese Kinh friend told me Han women too feminist and Vietnam girl very feminine. Chinese kinh like to go back Vietnam to find wife.