We enjoyed the FREE upgrading to Windows 10 in past year, now with the launch of Windows Server 2016, Microsoft wants to give us more, but it is not Windows 10 this time, it is about Windows Server, which is more useful for enterprise customers.
Microsoft announced a new promo plan yesterday:
_From September 1, 2016, through June 30, 2017, customers who switch workloads from VMware to Hyper-V can get free Windows Server Datacenter licenses when buying Windows Server Datacenter + Software Assurance. That ultimately means customers only pay for Software Assurance;_
So actually you still have to pay for software Assurance, which means the promo is not complete free, but the Windows Server license is truly free.
So if your company is using VMware, and it will not matter whether you use VMware or Hyper-V, as Virtual machines, and your business needs to create a Windows Server or even a Data Center for your business, you might consider this promo, please read Microsoft official blog to check detail information.