The largest Enterprise they had was only 25,000 Macbook a year. And IBM is 10 times the size of that order.
Most of the Enterprise I know, big or small are still very much Window based. The way Mac are getting in right now are through BYOD. However, most CIO see this as additional burden with Apple devices, and therefore most planning are still based on the Windows world.
CRM, ERP etc.. lots of business class things still are not available on Mac. Although there are alternatives, no business wants to try.
Hopefully IBM and Apple could use this chance to smooth out the quirks rolling Apple devices in Enterprise. And more company to follow.
Dont get me wrong, this isn't about getting rid of Windows. I am sure there are lots of people who enjoy Window 10. But when our company tries to switch over to Mac, we have had very little support and real world cases to based on.
P.S - Most of you working in the I.T / Computer Industry would have no problem doing so, but there are lots of industry out there who cant risk to switch even if they wanted to.