The USA could have achieved a peace very similar to Korea, where the South would have quickly become prosperous, while the North became a brutally poor buffer state for China.
We would likely have to have remained committed to our South Vietnamese allies until 1976 or 1978. The death of Mao and the purging of the hard-left in China would eventually have changed Chinese and world communist support for North Vietnam.
North Vietnam was aligned with the Soviet Union, and had cool relations with the ChiComs, in fact they fought a small war in 1979.
The American people don't have patience for a long foreign war like that. That is reality, at least under a democracy. It was certainly the reality during the Vietnam Era.
RE: The death of Mao and the purging of the hard-left in China would eventually have changed Chinese and world communist support for North Vietnam.
Speaking of North Korea, I expect the Dear Leader not to last very soon. Let’s hope and pray that whoever succeeds him gets to realize that Communism and belligerence doesn’t work.