Q. Will Windows Server 2016 Hyper-V support nested virtualization?
A. Yes. Windows Server 2016 adds supported for nested virtualization with Hyper-V, which means the Hyper-V role can be enabled within a Windows Server 2016 VM running on Windows Server 2016 VM. It also means that users can now create and share virtual machines. This will likely be most useful in lab and learning environments.
(Prior to Windows Server 2016, if users wanted to run Hyper-V VMs, the Hyper-V role had to be enabled on an OS physically deployed to a server. If Hyper-V was enabled within an actual VM, no VMs could be started; the hypervisor within the VM would not start.)