Are there any official announcements on the Safari front?
The only thing "official" at this time is that the Get Silverlight page now cites 31 Dec 2016 as the end of support for Silverlight in Safari. However, as I noted in this question it remains unclear if that date was set by Microsoft, or by Apple planning the end of NPAPI support.
Update June 2016:
On the WebKit blog the Safari team has announced that
When Safari 10 ships this fall, by default, Safari will behave as though common legacy plug-ins on users’ Macs are not installed.
The goal is to steer site to use HTML5. However they do say:
If you can’t replace a plug-in-based system in the short term, you may want to teach your users how to enable that plug-in for your website in Safari.
So the end of any Silverlight support in Safari remains officially unannounced.
Update Nov. 2016:
Webkit Release Notes for Safari Technology Preview 17 state:
Removed NPAPI Plug-in support from .safariextz Safari Extensions
but a date for mainstream release is not given. End of 2016 seems plausible.
Update Jan. 2017
From my testing Safari has not yet (1/11) been updated to include the loss of NPAPI support which was part of Safari Technology Preview 17. So far as I can see it is anyone's guess what their schedule is.
Firefox ver 52 mainstream release is scheduled for Mar. 7 2017 and according to here and the bug tracker. That is the last one to support NPAPI. This sure looks like the end of the road for Silverlight on Mac, unless you move to the ESR release v 52.x of Firefox, which will keep it available for a while. My reading of the ESR release schedule is that it may go to Q1 2018, but interpret that for yourself.
Update Mar. 27, 2017
Safari 10.1 was released and Safari still supports Silverlight, but it must be enabled with each use.