More older men and more pliable submissive woman.
In comparison to the 60 's 70 's where there were huge number of young people in the halls.
I would guess that there are more circumstances of people fading out before they are DFed as it were.
Finkelstein's comments are likely close to the money. During my upbringing in the 1960s, many many young people came into the organization who had not been raised in it. They often brought their particular "proclivities" with them and sooner or later started to engage in "unChristian conduct" and were reproved or disfellowshipped.
It was easier for them to cut their hair and clean up their physical appearance and wear nice clothes than to "change" their behavior. Being relatively "new" to the organization, with few family and friendship ties, being disfellowshipped was hardly difficult for them.
Nowadays, new ones coming into the organization as young or older adults who have no previous connection with Witnesses is relatviely rare.
Most have been raised in the religion and those who do stick around are on the older side.
When I see JWs out door-to-door (which is infrequently), they are invariably older women and a few older men. Also, locally, it is the same demographic who man the literature trolleys.
The ageing of the JW demographic has likely contributed to a decline in disfellowshippings - although I concede that there is likely significant regional variation in frequencies.