Win32 is defined as a 32 bit interface to Windows.  It superceeds Win16.  Is the newest (unreleased) 64 bit version Win64 or just .NET?

Tk uses the Win32 [API] and [MFC] classes to draw on the screen.  
 [elaborate on how it can be used for many other purposes and how Tcl uses it]

In the Microsoft newsgroups news://news.microsoft.com I (GPS) have noticed several people refer to Win32 as obsolete.  Is it really obsolete now?  Have they rewritten the core of Windows with [C#]?  Should Tk be modified to use the new API?