After reading through Mike Harsh's (Microsoft/Windows Forms) comments concerning the future of Windows Forms, I figured I'd throw in my two cents.
Reality check... Windows Forms is not going away any time soon. Windows Forms is the CLR wrapper around the Win32 windowing subsystem and messaging model. Windows 98, Window Me, Windows 2000, Windows XP and Windows Server 2003 rely on this technology... there's no alternative. Windows “Longhorn”, although will be sporting a new windowing subsystem (”Avalon”) will still have the Win32 subsystems in place. Win32 is not going away any time soon and Windows Forms is the .NET way of interacting with these subsystems; therefor will not be going anywhere anytime soon. Will there be improvements? Sure, but very minor. Is this a bad thing? No. It just shows how mature the technology is and as such doesn't really demand anything more than minor improvements. Anything major would potentially introduce huge problems due to incompatibilities and probably cause more problems than solve.
“Avalon” is the answer to changing the way things are done. Also, it's fair to point out there is already an alternative technology available on all the versions of Windows I listed... DirectX. Want to see what can be done with DirectX as a display technology in your own applications? Or... to view a small semi-preview of what “Avalon” will deliver to your applications? Look at Windows Media Center Edition PC and the associated applications. Those are developed using DirectX technologies on .NET 1.0.
The Windows applications being developed over the next three to four years will most likely be a combination of display technologies (Win32/WinFX).
[update] Wow, after reading through all the comments on the Mike's post... I followed to Dan Applemen's blog for additional comments. It's kind of scary to see how closely we mention some of the same things... he even mentioned DirectX ;-) There's a few other interesting points he brings up as well.