Well, this is an interesting question and one that I had been thinking for a long time now.
First of, how can South Vietnam survived? Well, let’s look at how the country fell. S. Vietnam’s government was very unpopular among its own people, especially in the countryside.
In the PBS documentaries series on Vietnam, they said “Whenever Ngo Dinh Diem speaks on the radio, there will be a person that comes to turn it off.” Ngo Dinh Diem is a family-style dictatorship that was named a Republic. During the first election, the administration and maybe..the U.S government bans the participation of other parties from fear that Communist may infiltrate from the election. That along with lack of transparency, Diem won the “election” with 90% of the vote and claim to obtain 600,000 votes even though only 450,000 went voted. Many citizens of S.Vietnam during this time felt betrayed and Diem continued to receive criticisms from the both Vietnamese and Foreign press. Again the PBS documentaries series in Vietnam, it said, “You can see how it [election result] affected their morale [the soldiers], they became lazier…”
We also have to consider how both the S. Vietnamese soldiers and Americans treated the local people, especially in the rural areas. Many kill or imprison innocent people who “looked” like Vietcong. And this in return making their relatives seeing the government in Saigon as unfair and unjustified and have a really high chance of joining the Communist side.
We also need to consider the U.S, especially how America’s free press affected the public’s opinions against the unjustified war. But that’s a bit too long now and I want to keep this short. [But this is probably the most important factor though]
Ok, so we know the simplified version of the problems, not how do we get rid of them. Well, we probably need to give people a better reason to fight and not becoming our enemies. So because in your scenario, we can’t get rid of Diem, so let say we give them a better life. More focus should be on helping the rural people with better housings, educations, securities, healthcares, and better crops and farming stuffs. This would hopefully gain support for the rural people. Also, maybe a good idea not to imprison them or kill them, even if they are communists. There are attempts of this in our history, but not as thorough, committed, and too corrupt. Among that, the press from foreign countries and internally should not be “good journalists” and only report what brings the Diem’s administration supports and cheerings. [Yea I just want to get into the scenarios]
Well, for South Vietnam, there are two possible scenarios.
The first one being that S. Vietnam became a developed country like S.Korea, Japan, and Taiwan. This meant that the New Democratic government in Saigon would have to do huge investment into its own population through better education, healthcare. As well as finding a way to stabilise the economy and increasing securities and limiting corruption to attract investors. This also meant that S.Vietnam should try to invest more in the creative industry and better banking systems so that new businesses can thrive. S.Vietnam will an economic powerhouse in South East Asia and Saigon will be an international hub for doing businesses, like Seoul or Tokyo. With big companies rival that with Hundai or Toyota. S.Vietnam will be an American success story and the country remains an important allies with the U.S from its founding until now.
The second scenario is that S. Vietnam never had a breakthrough in its economy and instead having a gradual growth like Thailand, Malaysia, or the Philippines. This meant that S. Vietnam remained “another SEA country”. Its economy is not too great but may still be better than the North overall. With its rich resources it can attract foreign investors but as you know, resources are not long term sustainable economic plan and will run into some troubles. The Democratic government of S.Vietnam will probably be not too free. Although in both situation, the U.S will have an advantage against China in the future since the super power can have military bases on both China’s east coast and southern coast.
But there is also a possibility that the country never democratise and remain a dictatorship. Which is really likely, like 40%–60%.
Now North Vietnam also had two possible scenarios.
The first one is that it become what the whole nation of Vietnam today. The first few years of peace, North Vietnam will be an economy dependent on the Soviet Union for tradings and aids. But after the collapse of the Soviet Union, Vietnam turns itself to play with the West. Talks with the U.S and its Southern brother begins, creating a possibility for reunion. The two brothers will be different for sure, but not as drastic as S. Korea and N. Korea since they haven’t separated for as long. Economic trades with the South increase the connection between the family and possible openess for tourists. Although, the S.Vietnamese government will still be very careful with doing business with Hanoi and try to send propagandas to the North. Kinda like the relation ship between China-Taiwan today. Or they could reunited like Germany.
The second one is that it becomes North Korea. Just like the first scenario, the North continues to depend on the Soviet Union until its collapse. Instead of joining the West and its brother who is now developing, it closes down its border except for Chinese. The North now becomes increasingly poorer, information is limited. Not much else to say, just look at N. Korea now. But there is a chance this may not happen. Unlike N.Korea, the Communist gov of the Vietnam has term limits and does not pass down from family (not entirely but just stick with this for now). There is a chance that one of the presidents may rethink about the country’s future and think that this whole thing is not good for the country and that it needs to open up with more than just China, but we may never know.
There are many things that I didn’t touch on like the Khmer Rouge, the “East Sea” issue, the border between them, how democracy in S.Vietnam would look like, etc. But that would worth like a whole book. Anyway, I’m still not very knowledgeable about this issue and the mess of the war in general. I have relatives who went through the war, things I learn in school and some additional research as my sources.