NSX vision is to support multi-hypervisor such as Hyper-V
VMworld 2016: NET9989 - VMware NSX, Network Bridge to Multi-Cloud Future - YouTube

But at the moment both NSX for vSphere (NSX-v) and NSX-Transformers (NSX-T) do not support Hyper-v
NSX-T supports vSphere/ESXi, RHEL KVM, and Ubuntu KVM
Hyper-v has their own network virtualization HNV and it does supports VXLAN based on this technet What's New in Hyper-V Network Virtualization in Windows Server Technical Preview
Most network virtualization will create their own network world in VXLAN
VXLAN to VLAN traffic would be routed and normally if you don't need to stretch/share layer 2 network between VLAN and VXLAN then you might not need hardware based VTEP function for bridging the two networks.
Yes you are right there should be no change required (as in re-architecturing) the physical network.
You would normally need VLAN/network for the VXLAN/VTEP transport and routing configuration between VLAN and VXLAN (dynamic or static)