This entire article is predicated on an unsupported assertion:
"There's a growing conviction among vendors that users want their virtual machines to be able to span different data centres – the vendors believe there's a high demand for the ability to pick up a VM workload in Sydney and move it to, say, San Francisco."
Which vendors? Not Amazon, that's for sure: they don't even support VM migration within an availability zone, let alone from one data center to another. Every fule kno, Molesworth, that best practices for cloud-based workloads involve treating VMs as mostly-stateless; if you need to move one, you fire up a new VM and shoot the old one in the head. Ask Netflix. And although a few VMware shops try to do cross-DC vMotion, the resulting network hairpins are horrible. Shipping a cold VM is a little better, but nobody does it by choice.