Well, a good few other species have been "managed into extinction" or are in the process of same, through a combination of putting a breeding halt on individuals held, calling animals owned by the collection elsewhere back and then ceasing to breed them, or refusing to co-operate with any attempts to import new blood.
Yes, I have noticed some of this attrition at work on recent visits- single sex herds of Asian deer/antelope such as Nilgai & Blackbuck, castrated Lions, apparently reduced(contracepted?) breeding in the gorilla groups to name a few. Diana Monkeys at PL now down to 0.1 apparently. GB Mangabeys non-breeders etc. What is the pattern in the Small Cat department? But it still leaves an awful lot of animals there which will never see their homelands...