@spivonious: I think we'll see WinRT slowly replace Win32 and .NET. I've finally gotten a chance to do some WinRT development that doesn't involve playing around with samples. A C# application sure looks a lot like .NET and WPF/Silverlight to me. It's a bit different, but it hasn't been painful. The future looks pretty good from here, and it certainly hasn't given me a reason to whine about technology "X" being dead.
Thant is why I would expect an Expression 5 (Blend and Web) for WinRT and HTML5. As others have pointed out Blend already supports Windows Phone 8 apps. I don't agree with Veusvius that VS 2012 should be the only tool for WinRT or HTML5 development, particularly from a designer perspective, at least not as it is now.