I found a vietnamese blogpost [0] seeming to say he was active until 1975? But also mentioned at the end:
"Then the boy seemed silently disappeared from the Saigon newspaper village.
No one knows the fate of What about the special reporter later"
There's also a comment saying that someone worked with him in San Francisco later on.
"That young reporter, also known as Hole M Cuong. Me and Cuong, worked in a San Francisco Wash Lab in 1977 until 1981, when I On vacation, I still work there and now I have the pleasure of mastering the Pentax-shaped machine that Cuong used to take pictures of at that time."
Perhaps someone more familiar with Vietnamese names could work out if he pops up somewhere else.
Thanks for this link! That 2016 comment appears to say he was known alternatively as Lỗ Mạnh Hùng or Lỗ m Cường. "Cường and I worked in a photo developing lab in San Francisco (image processing lab) … Cuong still works there". I'm not sure how many photo labs were still operating in the city in 2016 but Google Maps is listing only 20 there now. If he was 12 in 1968 he would be around 68 today.
"Hung eventually left Vietnam and ran his own photo shop in San Francisco, where he met former AP photographer Horst Faas in 1998, according to the San Francisco Examiner. 'They paid me $10 a picture,' Hung told Faas. 'It could support my whole family for one month.' A selection of Hung’s photos follows."
Amazing find. That mention of the Examiner led to the June 22, 1998 edition, front page of the Style section by Vietnam veteran Edvins Beitiks ("Ed"), "'Requiem' for A War, An Era":
"And at each exhibit, Faas has been approached by people with their own memories, people wanting to talk. In San Francisco, he was surprised by Jimmy Lo Hung, who took pictures for AP as a 12-year-old during the Tet offensive and now runs his own photo shop on Ninth Street.
Hung had brought a picture of himself in a helmet with PRESS across the front, and a laminated story headlined 'Boy, 12, in Dangerous Jobs'. 'They paid me $10 a picture,' he said, 'and that was big money in Vietnam. It could support my whole family for one month.'
Hung lost all his pictures and negatives when the North Vietnamese invaded the South. 'I only had a few minutes to escape,' he said, remembering that 'I was pulled aboard a helicopter filled with soldiers. They held my leg while it took off. So many soldiers trying to get on… some didn't, some dropped down.'
Faas, sitting beside Hung, said 'This kid, I didn't even know he was alive. I'm happy, really happy, to see him.'"
I wonder if the lab might have been Newtec Color Lab Inc at 122 9th St which appears to have been run by a Jimmy H Lo (Jun 1956–Jan 2018). There's also a tribute to Horst Faas at the Vietnam Reporting Project here: https://vietnamreportingproject.org/2012/05/remembering-hoor...
The article isn't saying that he was active until 1975, but only indicating that it is talking about history that precedes the surrender of South Vietnam to the North in 1975.
he probably left the camera behind for a steady job as soon as circumstances allowed for it. that would be quite in line with vietnamese work ethics. maybe even got a degree given that his father was also a scholar and switched to photography only for the sake of making a living in times when his academic education was not in demand. he also probably suffered from traumatizing experiences.
