"Enterprises will replace their Windows with tablets"
really? What can you do on your tablet in enterprises? You can have them only as an additional device. They don't even have any port where you can plugin something. And, you will have your tablets interact with whom?
At the end of the day, you need real machine running full blown OS to get shit done and not devices meant for playing with those face painting apps.
Ten years ago, were you saying the same about laptops?
Given that there are already enterprise users out there today on Android and iOS devices, this is a pretty bold claim. (And you can, in fact, plug things into tablets with both operating systems - they have USB support.)
These are not all being deployed as "secondary devices" - in many cases companies deploy them because they're cheaper to deploy and maintain than a laptop, which only makes sense if you're not also providing a laptop to the user.
Having companies run solely on laptops or tablets has nothing to do with whether or not there are enterprise tablet deployments. Your logic is flawed.
And then Microsoft makes money by selling 50-100 Remote Desktop CALs to replace those 50-100 physical desktops. The price per CAL is about 90% of the price per license of Windows. But add in the base price of the Windows Server license, and you're back to essentially the same price.
At first. But eventually, less and less will run on the 370^H^H^H Windows box, as people get native clients (or good HTML 5+ clients) for email, memos and spreadsheets, and only "that legacy .NET app we still have to use" will be on the big-iron rack in the DP donjon.