> VMware was cheaper opex by a factor of 4 and they were using ESXi as the hypervisor
How could it be 4x cheaper in Opex when OpenStack is an open source project with multiple competing vendors available if you want support? In terms of non-licensing costs, OpenStack has a few more services that need to be deployed separately, but I don't see that costing 4x, especially when those services often don't have VMware equivalents.
