Windows Sever 2008 R2 is no longer in mainstream support. Therefore, no hotfix will be released to enable the KMS activation of Windows 2016 for Windows Server 2008 R2 KMS hosts.
Windows Server 2012 and up are able to activate Windows Server 2016 KMS clients. Windows Server 2012 and Windows Server 2012 R2 KMS hosts need to have the July 2016 rollup update installed prior to changing the KMS CSVLK to Windows Server 2016.
KB3175615 for Server 2012 KMS servers.
KB3175614 for Server 2012 R2 KMS servers.
SQuin - Support Engineer