Microsoft has really adopted an if-you-can't-beat-em-join-em attitude these days. There were times when Microsoft and Linux were at such odds that an announcement like this seemed impossible.
The next smart move I'd love to see from Microsoft is similar to Apple's adoption of BSD as their base OS with the introduction of OSX, an adoption of Linux as the base Microsoft OS. They could stop wasting money on systems programming and focus on the UI and apps which is where they make their money anyway. Wine has come a long way with Microsoft's direct help it could support all of the existing Microsoft apps.
Because NT, as in modern NT, is pretty damn sophisticated. Switching to Linux really wouldn't be a step up for Microsoft.
As I said before, it's the crap that's been bolted on that really makes Windows feel like a dinosaur. It's the decades - literally decades - of backwards comparability, the lack of a proper package management system and the free reign that developers gets that makes Windows a mess. It's the multiple shells that try to coexist or the feature bloat of pass releases or even Microsofts past tendency to reinvent the desktop every few years rather than introduce incremental improvements. This is all issues independent of the kernel, syscalls etc - i.e. All issues Microsoft would have to address regardless of which core they chose to run. So switching to Linux wouldn't help them. If anything it would just make things worse because they would forgo the stable graphics ABIs in NT for the uncertainty that is Linuxes display server wars. They'd forgo their stable Win32 APIs and other libraries for WINE. They'd have to reinvent DirectX - who's support in WINE is several generations behind - and have to battle with the appalling state of Linuxes graphics card drivers. And that's just scratching the surface of the problems they'd face.
I do love Linux and find Windows to be a hateful platform, but pragmatically Windows switching away from NT would be the dumbest thing Microsoft could do. NT simply isn't an issue.
I also know that I do not look forward to a world with only one dominant desktop/server OS kernel. We need competition here and Microsoft adopting Linux would ruin that.
I doubt that will happen. There are innumerable man-hours of engineering sunk into Windows, and it has made them lots of money. Unless there were compelling proof that continuing to develop and support Windows was costing them money, and endangering other profitable revenue streams, Microsoft will likely keep Windows alive.
The next smart move I'd love to see from Microsoft is similar to Apple's adoption of BSD as their base OS with the introduction of OSX, an adoption of Linux as the base Microsoft OS. They could stop wasting money on systems programming and focus on the UI and apps which is where they make their money anyway. Wine has come a long way with Microsoft's direct help it could support all of the existing Microsoft apps.