What's sad, however, is that I don't think Apple really gives a shit about instant snapshots and other such things. Those are things you really want on file servers, which Apple once sold but doesn't sell any more.
From a purely outside view of watching Apple carefully, they likely has some plan to improve the filesystem on OS X/iOS/tvOS/WatchOS within a few more years. I'm not sure if it would go to ZFS/ZFS like directly. A variant worked into the growing CoreStorage efforts that lacks some ZFS benefits while also cutting way down on overhead would be my guess currently. They do still see a number of support cases and issues due to flaws in HFS+ in all their consumer products.