I seriously think this will be Microsofts last installable desktop operating system. After this it will all be embedded systems, "thin" terminals and "cloud" architecture
Customers will just have a pad / slate / thin client with an embedded operating system, and will access their files and applications over the internet.
Only thing in the cloud is your thinking Milo.
As long as Microsoft continue to have the emerging countries in their sights as a source of prospective and continued clients, there will be offline versions of Windows.
Same goes for government and corporate accounts with their laptop estate. Those who are already willing to embrace change will be starting to work on it now .... the more conservative accounts will continue to lean on their Microsoft account managers.
Sure there may be
a cloud version of Windows brewing (just like you have "home", "pro" etc. editions at the moment), but it ain't going to happen across the portfolio in the next decade or two.