Windows Server 2008 R2 is the first Windows operating system to be offered for only 64-bit processors. And Windows Server 2008 R2 can now support up to 256 logical processor cores for a single operating system instance, including enhancements in Hyper-V virtual machines which are able to address up to 32 logical cores in a single VM. These improvements not only guarantee more bang for your server hardware buck, but also offer better reliability with fewer locks and greater parallelism.
Yeah, that's what I think too. There will still be 32-bit as long as the majority of computers in the house or companies aren't strong enough to hold 64-bits.
In retrospect, it very well may be.
Server 2008 R2 is x64 only. From http://www.microsoft.com/windowsserver2008/en/us/R2.aspx
Thus, I can easily foresee the desktop OS going 32bit only.
After all, M$ dropped 16 bit support last year, didn't they