no. 1975 had a 7 year lead time. David Splane's spiel introduced the typical generation of Joseph. He lived to be 110. Anybody born (not just alive) during those 110 years is part of that generation.
My understanding (though I confess I haven't watched Splane's video) from the WT article about the overlap was not that they had to have overlapping lives, but that the generation applied only to anointed ones that had their "heavenly calling" overlap with the lives of anointed ones that had their "heavenly calling" prior to 1914. That's why fred franz was a good example for Splane's explanation because he would've been 21 in 1914 and likely had started partaking by then. So given that any overlappers would have to be partaking before 1992 to catch Franz (and well before that if you want to catch any significant portion of the first group of the overlap) that puts the minimum age of the second group of the overlap at ~40 today. But in 1992 almost all the partakers were much, much older (the youngest I'd ever met that was partaking then would be in his 70's now) due to the (now defunct) 1935 "sealing" of the anointed. So given that, the math works out pretty well to predict an end date of ~2034. That also has the convenience of matching the 120 years of Noah, which they've mentioned a few times in the last year or so.
Obviously, it could easily be twisted (just as they did with the original generation teaching) to extend the overlap well into 2075, but that's not what they're saying now (even in the literature they've said that the second group are themselves getting up in age) and I think they're more likely to set a date than to revise the teaching to extend the date (until they absolutely have to)