I don't think I've worked anywhere where there was a simple way to switch cloud providers with the push of a button. Even migrating to different locations within a cloud provider isn't trivial. You'd have to invest a lot of engineering time from the beginning to get this kind of capability, and you may never realize any value for all the pain.
Yep; not easy at all ... if it were easy everyone would do it :) I think with tools like puppet and orchestration tools like heat, etc it is getting closer to being easier.
I did got to a Netflix talk once where they said that while moving from AWS would huge, they had a plan and I think from memory they said it would take about a week.
