I think this is destined to eventually replace their plugin-based version at http://maps.nokia.com/ - at least for WebGL browsers.
I wouldn't even be surprised if MS adopts Webkit.
For MS to leverage IE 'dominance' would be a losing game. They no longer have control over the web. I have no doubt that MS will attempt to control the web with W8 but I think they will lose and do so quickly.
But – as is already obvious – dominance is indeed no longer something they have, will realistically achieve ever again or are able to leverage. If they want to have any say at all when it comes to the web’s future they have to play the standards game. They have to cooperate.
Microsoft is keenly aware of that (though maybe not entirely comfortable), as is evident from the direction they took with IE.
The real problem lies not inside the engine but inside Microsoft themselves. Specifically, within the .NET group. I know everyone on Hacker News loves Ruby, so I'll use that as an example. Microsoft wanted the dynamic language stylings that Ruby offered, so they spent 3 years developing IronRuby that ran on the .NET CLR. Then they suddenly dropped it without warning. Why? Because they had extracted everything they wanted from it. Keeping the technology up to date would not give them anything more than what they already had. Microsoft benefited from it, and when they no longer did, they dropped it. Everything that happens inside Microsoft's core is to strengthen their sellers: Windows and Office. If Windows or Office needs a new technology, they will take it, use it, and .NET-ify it until it becomes proprietary.
If they were to swap Trident for Webkit, it would be the same thing. IE11 built on Webkit for a few years, their development staff would learn from it, and the next release would see Trident 7 (IE12) back in form. Microsoft takes with only nominal giving because that's great for business. They can learn from outside technologies, then use that knowledge to lock people in tighter with better tech.
It's been a while since we've seen Microsoft in true form, pioneering and leveraging their weight to shape the market for their benefit. What we have right now is Microsoft in damage control mode. Moving to Webkit would be more of that, strengthening Trident by sucking the essence out of Webkit or Gecko, directing the flow of HTML5 (and pushing for MSHTML6 afterwards) would be the return of the powerhouse. It'll be interesting to see where things go, but even as someone who sees Microsoft as the best tool for the job in some certain situations, I would't place any bets on Microsoft being the dominant force on the web... ever. Luckily (for them), desktops aren't going anywhere anytime soon.
edit - I should add that, to your point (and mine), Microsoft already does use Webkit where it is advantageous for them: Mac OSX. Instead of continuing development on IE for OSX, they switched Office to Webkit for the Mac. I'd have to believe Trident would have suffered without that move (circa Office 2011).
Instead, MS is pushing performance improvements and hardware acceleration for Canvas and SVG. This is NVIDIA, but to give an example of the possibilities:
http://developer.nvidia.com/nv-path-rendering
IMO, focusing on these isn't a bad thing, because these 2D technologies are substantially easier to use (e.g., SVG is declarative and integrates with CSS). Though, WebGL is obviously more expressive.
We may also see some WebGL-derived technologies make their way back into CSS + SVG. Similar to SVG filters for CSS:
http://www.w3.org/Graphics/fx/
Proposed GLSL shaders for CSS:
http://code.google.com/p/angleproject/)
I would love to see shaders on CSS, but GLSL is such an ugly layer to add on top of a fairly nice design. Notice how the SVG filters are so much simpler to specify than the GLSL-on-CSS proposal.
I would much rather that Adobe designed a more restricted, declarative little language which would easily compile to GLSL, than bolt an almost-turing-complete C variant on top of CSS which is hard to reason about, hard to guarantee safety (most of the webgl-crashes-video-drivers issues have still not been solved, aside from the hamfisted "we will block webgl if we see this set of drivers" solution), and hard to interoperate.
Why?
Games.
WebGL is really impressive technology. The combination of a widely-deployed widely-used language (Javascipt) with high performance graphics (WebGL) make for a surprisingly capable platform for cross-platform game development. Once WebGL arrives on mobile and a full screen gets added on the desktop, I think it will become very, very popular.
Of course, the graphics capabilities aren't ask good as full-power OpenGL or Direct3D, but they're plenty good enough for a lot of applications.
This is why I think that Microsoft will be forced to support it: they'll have a hard time convincing the public to buy into Microsoft's platform if the public can't play their favourite games on it.
In the meantime, Chrome Frame provides WebGL inside Internet Explorer and you don't even need admin rights to install it :-)