Those aren't private datacenters. Amazon/Azure/Rackspace/Google Cloud are public datacenters providing services for customers, so they will obviously be using virtualization. Personally I think public cloud is going to kill private cloud altogether, but that's an entirely different discussion. But in the specific case of private datacenters, I believe, virtualization is dead, and many of my colleagues share the same opinion. Just because it's not common around the world doesn't mean that the change in trend and thoughts hasn't hit an inflection point. Virtualization has done an amazing job, and there's a reason why it has become so popular. But just like all other technologies, I think its going to be passed for something simpler that scales better.

> Mesos is a form of virtualisation

Is it? To me Mesos is a system for job management across a heterogenous pool of compute resources.