That sounds like you're suggesting that Microsoft wouldn't care what was installed locally to be able to net-boot / run the rest of Windows.
I think it's all but certain that they'd want user's computers to to boot into something they made, or at the very least, slapped their branding all over, even if that was only a wrapper for their web browser.
I can definitely see them going down the line of saying that their online apps aren't guaranteed to work under any other system, going so far as to throw in a few deliberate stumbling hazards for anything that isn't theirs. (Until anti-trust, etc.)
And thus, dual booting will still be something that people do. Even if - as you clarified - they're not going to cripple that as well.