I wouldn't say it's abject poverty. But it's certainly far less developed than South Korea or Taiwan, which is the most likely counterfactual for a free South Vietnam. OTOH you could possibly argue (though far more speculatively) that North Vietnam would've turned into North Korea from the paranoia, isolation and humiliation of a loss.
Those two countries were impoverished military dictatorships for the first few decades as well. They also received significant economic support from the United States.
