My concern is that while MS has missed the boat in the mobile space, Android is late to the party, or not even looking at, the ARM-based workstation space. I can't replace my work computer with an Android-based laptop, it's just a whole different space, content consuming rather than production.
MS on the other hand is doing their dual UI thing in Windows 8 with a traditional UI paired with Metro. They're late to the mobile space, but they'll be the only ones at the table in the ARM-based workstation space (I mean, there's plain linux, but that's still not a household name), and they can use that position to bully their way back into the mobile space by locking linux/Android users out from higher-end ARM machines. Not a whole lot of people want linux on their phone now, but when they start getting acquainted with this notion that their workstation OS has been designed to run just as effectively on their phones/tablet, that might change.
We've seen it before with when linux got the jump on MS with netbooks...eventually Microsoft manages to shift users into thinking non-MS machines are inferior, hits all the right pricepoints, and next thing you know nobody is shipping linux netbooks anymore. I can see that happening again with linux and Android on ARM laptops, except this time around we'll be screwed. We'll end up being relegated to running linux on ARM machines that were designed for Android, and the higher-end stuff will be off-limits. And the machines designed for Android will become scarcer if Microsoft succeeds in making the in-roads they're trying to making with Windows 8 and Metro.
It may be a bit gloom and doom, but it seems just as realistic to me as Android taking over the mobile space seemed did when I bought my G1. So I find it pretty scary...