http://forums.macrumors.com/posts/23234541

[B]Some milestones[/B]

Possible chronological order:
[LIST=1]
[*]APFS developer preview in pre-release 10.12
[*]APFS developer preview in the first release of 10.12
[*]APFS developer preview or beta in pre-release 10.13, to include boot from APFS
[*]APFS in the first release of 10.13

[*]APFS to ship (first release) in 2017
[*]APFS to be the default file system for all Apple products, although I don't yet know [URL='http://forums.macrumors.com/posts/23061455']whether, or how, Time Capsule will transition to APFS[/URL]
[*]10.11.x to gain support for APFS data volumes.
[/LIST]
[USER=230315]@KALLT[/USER] would you expect a similar order?

I expect 4, 5 and 6 to be broadly coincidental – around the same time of year, not necessarily the same date.

[B]For the operating systems that are commonly associated with Apple[/B]

I can't imagine APFS as a default for any release of iOS, tvOS or watchOS before it becomes the default for a release of macOS. Whilst the file system might become release-quality for any/all of the first three before macOS, strategically it will make sense for Apple to not formally release APFS until it's perceived to be of suitable quality [B]for all four[/B] operating systems. (Some Mac users are pleasingly difficult to please … to be treated as second-, third- or fourth-rate after waiting so long for a good storage system would cause a mild outcry.)

[B]Those four aside[/B]

[URL]http://apple.stackexchange.com/a/106026/8546[/URL] shows that Time Capsule runs NetBSD.