Pittsburgh and Cleveland are both apparently down to one active made guy (Sonny Ciancutti and Russell Papalardo, respectively - the former is about 80 and the latter is like 67). There is a handful of other made guys in those two cities but they are apparently retired. Once those two guys are dead, both families will be completely extinct.

What seems to be the case with Buffalo and Detroit is that, although they both still have like 20 members left, the membership got old and rich. So the families have stopped doing much (if anything) even though they have a lot of made guys left. In my opinion (and I hope this doesn't "offend" anyone, haha), the Chicago Outfit also seems to be in the process of turning into this kind of family.