I actually considered writing my dissertation on a similar topic! The linked source doesn't seem that reliable, but it jives with what I've been able to find out. A major problem with figuring out what happened to the Kit Carson Scouts is that those who served in that program don't like to talk about it. Those who stayed in Vietnam would be considered traitors, and as such would face harsh punishment (indeed, many were sent to re-education camps). It's a little more complicated for those who came to the US after the war, but they would also want to keep quiet about it. Basically the problem there is that even though they defected, they were at one time associated with the NLF. Most Vietnamese-American communities remain quite hostile to the communist government, and so former Kit Carson Scouts risk social censure if they come forward. Finally, there weren't that many Kit Carson Scouts to begin with, and it was a dangerous job. So it might be an unsatisfying answer, but it's just very difficult to tell what happened to those scouts that survived the war.