I use Ken Cook as a model. He graduated High School in 1980
Based on Sanderson's blurb when he was appointed to the GB, I calculated his high school graduation as 1983, making him maybe 56 or 57 now.
But given his obesity, yeah, he'll be just a couple Big Macs from a massive coronary after another 10 years or so.
Anyone younger than them, and you stretch the credulity of "young guy's official anointing overlapping with the lifetime of Franz". You'd need to have guys who started partaking as teenagers then followed all the rules to remain "exemplary" and on the fast track.
So yeah, "new light" on "this generation" will probably come in about 10-15 years time.
Anyone want to bet on whether they'll go to a "3-ply overlap"?