The Chinese did invade Vietnam in 1979, only to pull back two months later after suffering heavy casualties, so that already happened, and they are unlikely to repeat the mistake. In any case, it would be a mistake to let the past dominate the present. China needs to be contained, and this consideration ought to come before trying to get some kind of self-gratifying revenge over events that happened 40 years ago.
Just prior to the attack, China sent nearly 2 million troops to their border with USSR. This pretty much proves their intentions in Vietnam. Just kicking the dog so to speak. USSR did not come to Vietnam's aid. Viets got pissed.
Vietnam kept most of their troops near Hanoi. China looted/pillaged the border areas of Vietnam as they withdrew.
It is interesting to note that China supported the Mujahideen of Afghanistan in their fight against the Soviets. Trained the Muj in China proper and armed them as well.
Nothing wrong with playing regional power politics with China by using Vietnam (I’m a Vietnam vet FWIW). Most of the Vietnamese who fought us are dead, except for a few Ho Chi Minh cronies (Vo Nguyen Giap is well into his nineties). They have long been succeeded by a younger generation with no memory of the 1945-75 war and who are eager to build relations with the United States, if for no other reason than to have us counterbalance the Chinese.
Anti-Americanism in Vietnam is a nearly forgotten hiccup in their three thousand year national history. But during that entire period China has been their most hated enemy, and the PRC’s current burgeoning military & economic power won’t serve to diminish that profound animus.
As noted, the Chinese attempted to invade Vietnam in 1979 and got bloodied for it. Their ability to project power in the Pacific Rim has yet to be demonstrated; they are much more successful in suppressing domestic insurgencies.
Communism in Vietnam is similar to communism in China, an excuse for the ruling elite to hold onto political power. That indicates that they will not reject Realpolitik in order to serve their national interests. Vietnam is not Cuba nor North Korea; those two are ruled by fanatical Stalinists.
There’s room for pragmatic interaction with the Vietnamese, they’re not stupid.