Google provides a nice and basic “Savings Calculator” which could give you a feeling about possible savings in your IT environment in case of a migration to Chromebooks.
For most of the Office workers Chromebooks definitely make sense. They are never using the full functionality and computing power of standard Windows PC’s or Mac’s.
With Chromebooks IT departments could definitly save a lot of money for client deployments, operating system upgrades, hardware maintenance and software package distribution.
Anyway it’s clear that for a small number of special use cases in a company, power workstations will remain (e.g. Software Developers, Video cutters, …)