While the T-28 and A-1, and even the A-26, did a grand job in the early days Vietnam, isn't it just a teensy bit simplistic to think that they could do the job today?
On the one hand, they really were operating in an environment where the threat really did come from blokes in sandals with AK-47s - or even bolt action rifles, and with nothing like the heavy calibre threat, and certainly without MANPADS.
In any case, by the end of Vietnam, the loss rate among such types was eye-watering, and certainly way above what would be acceptable today.
And were they capable of sufficient precision, avoiding the kind of collateral damage that would be unacceptable today?
I'd love my own private Skyraider to tool around in, and I reckon I could sharpen up enough not to be a complete danger to myself and everyone else. But I wouldn't expect some poor sap to strap one on and venture into the modern battlefield, facing sophisticated AA and SAM threats.