if you have a really beefy single bare metal hypervisor (typically xen or kvm) it's totally possible to give it 100GbE to the switch now:

http://www.silicom-usa.com/pr/server-adapters/networking-ada...

I don't have anything this serious in my own production use, but I'm thinking of machines like dual socket x 32-core per socket xeons, or amd epyc, with 512GB to 1TB of RAM.

then pass vlan tagged traffic off one switch port, to each specific guest VM, of which there might be dozens to 100+ VMs, as subinterfaces of that.

I've seen some 160GbE links in datacenters - 4x40's - how much they were actually utilized, I have no idea.