Transforming a sizeable development organization from "classic" development practices to Agile cloud development is something I talk about a lot. Bhavik Shah, who used to work on our team, left Microsoft to go to business school and now works a Mckinsey, recently wrote an article on that transformation process. Buck Hodges, one of our Engineering Directors worked with Bhavik and others on it.
It's a nice read: https://tmt.mckinsey.com/
The link is a link to the Mckinsey home page - I don't have a perma-link to the article. It's on the front page as I write this. The article is titled "From box to cloud: An approach for software development executives"
Brian