In the latest Microsoft SfB Video broadcast, Microsoft gave out some new details on the windows client. The video isn’t on YouTube yet, but is available here.
The big news was offline messaging is coming to the windows client, and there was more explanation of the MSI and click to run update models, I’ve written about them previously:
Understanding Office Click-to-Run, Branches, MSI and Skype for Business Client Versions
Office 2016 C2R Current Branch for Business is GA and it has a New Name – Branch is now “Channel”
Here are some screenshots of the key information if you didn’t have time to watch:

Any idea if offline messaging is for Office 365 only or also for on-premise (what are the requirements esp. regarding the version of Exchange)?