This is rapidly changing. When I took over technical ops at my employer, we were 100% public cloud. I quickly moved us to private managed cloud and quadruped our capacity for 20% less spend. Now I'm in the process of preparing us to move to colocation, where I'm certain that I can save another 40-50% over three years. What's made this possible is technologies like CoreOS, Kubernetes, and Ceph. We are working on automating the bare metal network management pieces but I am confident that we will soon have an environment that can function in colo without onsite staff. If we automate throughly and pre-cable racks, adding capacity is as simple as using a colo provider's remote hands service to rack and stack new hardware every quarter or so.