Adding support or even putting emphasis on HTML5+JS has nothing to do with abandoning .NET per se. Microsoft would be dumb to do that, because supporting a truly platform-independent technologies, like pure HTML5+JS would mean you are no longer bound to Windows. Therefore you can be sure that even though HTML5+JS will obviously play a key role in Windows 8, they will do that somehow bound to .NET.
The above of course doesn't hold true for Silverlight, which is a technology directly competing with HTML5+JS, so it makes no sense to support that too if you're putting your eggs into the HTML5+JS basket. But since SL was on the way of going extinct anyway for years now, it would be not much a surprise if MS would actually "kill" it.
Of course they would never announce it to be "dead", just "forget" to supply any more updates to it beyond Windows 8.
For many years now, commentators have been giving up on Java or Java Enterprise Edition for dead as a legacy technology or platform. There have been plenty of articles written about its imminent demise. But it’s still around, and by all indications, going strong.
What caught my attention in Niel McAllister’s latest InfoWorld post was the assertion that the .NET Framework is also being sucked into the same alleged abyss into which Java is falling.
The infighting around Java Community Process has been making a lot of headlines as of late, considered by some as another nail in the Java coffin. Java on the wane? Old news.
But .NET on the wane? McAllister doesn’t cite direct evidence of this, but says Microsoft’s tendencies to pull back from technologies doesn’t bode well for the framework:
“For a time, Microsoft funded development of IronPython and IronRuby, versions of two popular scripting languages that ran on the [Common Language Runtime]. But Microsoft has since backed away from these dynamic languages to focus on C# and Visual Basic, leaving IronPython and IronRuby developers in a lurch. Now some Microsoft shops are wondering whether other .Net technologies might soon meet the same fate. For several years, Microsoft has been encouraging developers to build UIs using Silverlight, a proprietary Microsoft technology for constructing rich Internet applications…. Yet for months now we’ve heard rumblings that Microsoft may be de-emphasizing Silverlight in favor of Web standards such as HTML5 and JavaScript…. How can enterprise developers be expected to view .Net as a strategic platform if Microsoft can’t even get its own strategy straight?”
McAllister calls the two enterprise frameworks to be “lumbering technologies” in the age of cloud and lightweight scripting. Indeed, both Java EE and .NET came of age more than a decade ago, when there weren’t as many options for securing ready-to-go plumbing that could support Web-friendly applications. So there’s a healthy installed base that’s been around for a few years. But there are now a lot of options for companies and developers. The big question is: how likely is a startup or new enterprise project likely to built on Java or .NET?
silverlight is still doing well. If someone learned sliverlight, there are plenty of jobs asking for it. 
