The XAML/C# stack is called many different things within windows. Silverlight and WPF are just two names for it. Keep in mind though that even things that are branded silverlight (desktop/web apps and wp7 apps) aren't even the same thing. The WP7 API differs heavily from the desktop API. The XAML/C# stack for metro apps is also just a very small subset of the silverlight stack.
Silverlight may very well be going away, but XAML/C# isn't. The only thing that's most likely disappearing is the push for it to be on the web and the name "silverlight" itself.
Sort of. That is, traditionally XAML has been used primarily for Silverlight & WPF applications, but it's actually just a declarative language used for laying out (usually) Silverlight & WPF controls.
It's sort of a combo HTML&CSS. So your statement in that vein would be like "Isn't HTML&CSS just another name for Gecko and/or WebKit?"
That said, even though it looks like XAML may be used for new WinRT-based apps in the Windows Metro stuff, I'd be surprised if it survives the deaths of Silverlight & WPF.
http://blog.discountasp.net/build-conference-developers-have...
With Microsoft diagrams, the importance of the technology is proportional to the size of the box.