>> One final point of interest is that the much-vaunted 'Wintel'
partnership that drove virtually every other OS and CPU architecture out
of business is nowhere to be seen.
Good observation, and a little puzzling to me too. Of course, I've always seen how Intel benefited from the deal... but very little in the way of Microsoft's gains - unless Intel just promised not to compete with them in the area of development software.
I wonder if this could ever lead to an ARM version of Windows for the desktop? Of course, it wouldn't be able to run anything except Java, .Net, and specifically ported apps.
Microsoft's primary benefit, I'm guessing, was mutual advertising and branding. Back in the early 90s, Apple and IBM's OS/2 would've been primary competition, but there were other programs. Windows, after all, was still a program that ran "over" DOS, not an app environment itself in any sense of the word.
Microsoft has done Windows ports to other architectures before (Alpha and Itanium both spring to mind, + Windows CE itself) so I'm guessing that yes--if a sufficient number of non-x86 chips start grabbing marketshare in an environment where it makes sense to offer a full OS rather than Windows Phone 7, they'll port something over.