One of the key pillars on which the vision of NfV rests is optimized (meaning fast) cpu based packet processing. Sometime referred to as datapath processing in the cpu-mem complex without the need for any asic acceleration. No requiring any asic in the data path makes the cpu fungible (changed at will) and dramatically brings down the cost of network functions.
As we look at optimizations, we may also want to looks at why we have the ethernet I and II packet types and why the MTU min/max/jumbo packet sizes were arrived at. Do we really need the ethernet packet when the conversation is between two virtual machines on the same node? Even across the host boundaries, but within the same data center, it is possible to have a conversation without having to create ethernet frames.
Hopefully we won't take existing VNFs and simply make OVFs out of them and run on a favorite hypervisor. Real NfV would involve refactoring the VNFs to use packet gateways for certain function and use standard RPC/IPC mechanisms for others.