The impact of using NSX without a transport zone is that you won't be able to create any logical switches (VXLAN networks). The rest of NSX (DFW, Edges, etc) should work. Have a look at the VMware NSX Design guide. the TZs are explained there, plus there are a few pictures of where they fit in the NSX picture: https://www.vmware.com/files/pdf/products/nsx/vmw-nsx-network-virtualization-design-guide.pdf
The impact of using NSX without a transport zone is that you won't be able to create any logical switches (VXLAN networks). The rest of NSX (DFW, Edges, etc) should work. Have a look at the VMware NSX Design guide. the TZs are explained there, plus there are a few pictures of where they fit in the NSX picture: https://www.vmware.com/files/pdf/products/nsx/vmw-nsx-network-virtualization-design-guide.pdf
