If there was a South Vietnamese 'Taiwan' planned on the islands, wouldn't the [North] Vietnamese try to capture as much of the South Vietnamese army, wealthy and important personalities and political leaders as possible by accelerating the capture of Saigon or the destruction of much of the South Vietnamese navy, planes, civilian vessels and fishing boats? As for the Americans and their allies helping in the evacuation, once they withdraw from the fighting, they ain't evacuating refugees.
That's the big problem with the scenario. This pocket is too small to survive against such a brutal and well equipped enemy. There will be plenty of people who want to escape communist rule as history shows but this is too small an area. Given that the US refused to aid the south when it could well have been decisive I can't see the north simply pounding the pocket into submission. Their ruthless enough to slaughter the entire population and Russia will make sure they have enough ammunition so I can't see a free Vietnam survive.
Steve
The only thread or 2 mentioning about a small pocket or an island of South Vietnam being a 'Taiwan' analogue discuss[es] about the issue of space, supply, North Vietnamese siege techniques and American intervention that is very likely needed, as well as North Vietnamese wishes to reunify Vietnam for good permanently and prestige. And, after Saigon, the small pieces of land to the south of the Mekong are really too small to be sustainable anyway. Once the South Vietnamese run out of supplies and the North Vietnamese bombardment on the rebellious enclaves perseveres without American intervention, it's just a matter of a few years at the maximum and more like months, if the Vietnamese prolong a total war campaign without assaulting the island
and enclaves.