Microsoft knows business. That’s what they bring to the table. This will continue. The only question is about how.
Open sourcing Windows also would relieve them of the onus of having to fix every bug in Windows back to the beginning of time. Already they are kind of backtracking on the “will not maintain XP” position and sending out limited security updates.
Indeed MS has the corporate network Server market cornered. Active Directory & Exchange is so easily adaptable to virtually any business. Regarding virtualization, I still prefer VMware by far.
My current shop is mostly VMware running on HP hardware, hosting MS & Linux Servers, attached to EMC SANs for storage. With Cisco networking hardware(including wireless).