NSX assumes server virtualization in some form, be it with an ESXi cluster or a cloud built using other hypervisors, either public or private. VMware is gearing up to push NSX as a hybrid networking layer that can span the big public clouds like Amazon Web Services or Microsoft Azure, but it does not have the same hybrid story that it can so easily tell with its ESXi stack. While the vCloud Air network of public clouds created by VMware itself and its service provider partners can offer compatible clouds with the familiar ESXi hypervisor and consistent management tools across on-premises and public cloud infrastructure, the scale of vCloud Air has nothing on Microsoft's Azure, and moreover, if Windows Server shops want to learn a new management paradigm, as they will have to do when they go hybrid, they might be more apt to shift to Hyper-V and learn Azure Stack for on premises and use Azure for public cloud capacity.