There are both costs and benefits to this.
Now they cannot work locally at all whenever the internet is down, say they lose a router or something, then they have nothing. Also, an hour per day wasted booting up? I question that... just don't reboot every day if that is the case.
However, there is a big saving not mentioned. Previously, they would have occasionally lost a PC. This would require reconfiguring a new PC and it doesn't matter how you ghost drive it or have backups, it still is a huge productivity loss as the person reconnects to printers, outside services with encryption, etc.