I can attest that persistent storage is the hard part! Full disclosure, I work for a company[1] who makes a persistent storage solution for containers/Kubernetes. We are absolutely seeing that our large customers (folks like GE, Verizon, Dreamworks, Comcast, etc) are running "cloud native" applications on-prem as well as in the public cloud so this is a really smart move for Google.
[1] https://portworx.com