I am part of the 1975 generation and those born in that year are approaching 40.
If we assume they had to be 10 to understand any of 1975, they would be approaching 50.
2019 - 1975 = 44, 2019 - 1965 = 54.
Those guys are halfway through their 40s & 50s. Time stands still for no man
(I am an "age of understanding" dude; even though I was just a little kid, I clearly remember the 1975 hype, both from the "literature" and the talks).
Oh, and back on topic - as outlined in the OP, most of the kids I grew up with attending the KH are no longer JWs - I'd say probably 75% are long gone.