This has been talked about for a while now, so why all the surprise? Furthermore, even though legacy Windows apps won't run on ARM, it would appear that MS has been working for a long while now on getting a new version of Windows ready on ARM (which is what Windows RT is right now). But MS is wanting a full 64-bit version of Windows on ARM, and they are working full speed to do it:
http://techland.time.com/2012/07/16/arm-vs-intel-how-the-processor-wars-will-benefit-consumers-most/
http://www.techcentral.ie/20228/arm-working-with-microsoft-on-64-bit-windows-os
http://blogs.msdn.com/b/b8/archive/...ndows-for-the-arm-processor-architecture.aspx
And since Apple's custom chips are built on an ARM architecture, it is highly likely Microsoft's new 64-bit Windows for ARM would run on those chips. What that means is, we could still run Windows-for-ARM in virtualization or Boot Camp, but we simply would not be able to run x86 Intel Windows and associated software. For that, we'd need to keep an old PC or Intel Mac around.
All said, it doesn't look like Apple would really lose much if Windows eventually is compatible with Apple's ARM-based chips. And so long as they are just as fast or faster than Intel's DESKTOP chips (such as those in current iMacs, like the i7 QuadCore's), I will be largely satisfied.