How do I license SQL Server 2016 on a "Per Core" model in a virtualized environment?

There are no changes to the licensing requirements in this case. There are two ways to license SQL Server 2016 on a "per core" model in a virtualized environment.

License Individual Virtual Machines (VMs)
Partners must purchase a core license for each v-core (or virtual processor, virtual CPU, virtual thread) allocated to the VM, subject to a four core license minimum per VM. For licensing purposes, a v-core maps to a hardware thread.

Licensing for Maximum Virtualization
Partners who have licensed all physical cores on the server can run an unlimited number of instances of the software in any number of OSEs (physical or virtual).