Although Windows Server 2016 has been officially released since 26 Sep 2016 (Ignite conference in Atlanta), it is still not listed as a supported server operating system platform to install or operate Skype for Business Server 2015. Likewise, this applies to domain controllers in the Active Directory environment.
Per “Server requirements for Skype for Business Server 2015” (TechNet – Topic Last Modified: 2017-02-23):
Windows Server 2016 is not included in this list right now, but we’re planning to add it as a supported option after Skype for Business Server Cumulative Update 5 is released. Until then, please don’t try to use Windows Server 2016 as an OS for your Skype for Business deployment today, as it’s not yet supported, and we don’t recommend it. And check back to this page once the cumulative update is released to confirm Windows Server 2016 is added to our supported list at that time.
Additionally, PowerShell 5.1 is delivered in Windows Server 2016 and Windows 10 Anniversary Update (Build 1607). On supported legacy and down-level Windows operating systems, you can apply Windows Management Framework 5.1 (KB3191565) to update to this current version. Nevertheless, WMF 5.1 is marked as incompatible with Skype for Business Server 2015 (or for that matter Lync Server 2013 and 2010).
The golden rule “If it ain’t broken, don’t fix it” should apply (particularly on live production systems)!
Announcing the launch of Windows Server 2016 (Hybrid Cloud Blog link)
Windows Server 2016 RTM, System Center 2016 RTM and Azure Stack TP2 – now available (link)
Requirements for your Skype for Business environment (TechNet link)
WMF 5.1 Product Compatibility Status (Last Updated: 1/31/2017 link)