The 'official toolkit' Metro is XAML + (C++ or .NET or MSHTML5). I've been told by a (true) Silverlight/WPF expert that the Win8 XAML most resembles the Silverlight API.
Silverlight used to be promoted as:
* Flex/Flash compete
* Public web compete (I never recommended it for such)
* line-of-business (not publicly available) apps
* (recent) Windows Phone 7
Silverlight is now promoted as:
* line-of-business apps
* Windows Phone 7, but maybe Win Phone 8 will look more like the Win8 Metro XAML (I don't think they've said anything yet)
Metro is now promoted for:
* Win8 tablet apps
* Win8 native apps(? who cares I guess?)
* possibly Win Phone 8 apps
I don't know what apps you write, so I don't know what your specific roadmap may look like. I've leaned toward recommending web apps over "client" apps for .NET devs the past few years, and will heavily lean that way going forward. ASP.NET MVC skills translate easily to open source/competing web frameworks. WPF or Silverlight developers can't say the same thing.
If from a developer's viewpoint, XAML looks identical to Silverlight, and there are the same number of people working on XAML for the Windows team as there used to be working on Silverlight for DevDiv, does it matter?
But I bet you're feeling betrayed. I understand. I felt a little betrayed a few frameworks ago. Post-betrayal, I stick to focusing on transferable skills and JIT learn the rest of .NET. I'm on a WPF project now, have not studied WPF deeply.
My advice: if you have any say in the matter, try to work with ASP.NET MVC as opposed to the .NET alternatives, so your skills transfer.
Footnote: I don't know how many worked on Silverlight/WPF/WP7 versus how many work on XAML now. I assume XAML will march on. But no one will care unless/until the Windows tablet is successful.
I assumed that XAML was the silverlight team (why duplicate effort) and if silverligth is gone how much core knowledge stays in XAML?
Personally I stuck to C++ and moved MFC->wx->Qt !
.Net is interesting for the way it allows things like Ironpython and F# in as first class languages and wpf is fun to play with, but if you can't write something like Office or photoshop in it then it's just a toy.
Silverlight used to be promoted as:
* Flex/Flash compete * Public web compete (I never recommended it for such) * line-of-business (not publicly available) apps * (recent) Windows Phone 7
Silverlight is now promoted as:
* line-of-business apps * Windows Phone 7, but maybe Win Phone 8 will look more like the Win8 Metro XAML (I don't think they've said anything yet)
Metro is now promoted for:
* Win8 tablet apps * Win8 native apps(? who cares I guess?) * possibly Win Phone 8 apps
I don't know what apps you write, so I don't know what your specific roadmap may look like. I've leaned toward recommending web apps over "client" apps for .NET devs the past few years, and will heavily lean that way going forward. ASP.NET MVC skills translate easily to open source/competing web frameworks. WPF or Silverlight developers can't say the same thing.