Microsoft has hinted at their long-term expectations for the PC market. These are supposedly the system requirements for the next version of Windows:

Longhorn to Steal Limelight at WinHEC: Microsoft is expected to recommend that the 'average' Longhorn PC feature a dual-core CPU running at 4 to 6GHz; a minimum of 2 gigs of RAM; up to a terabyte of storage; a 1 Gbit, built-in, Ethernet-wired port and an 802.11g wireless link; and a graphics processor that runs three times faster than those on the market today. That's according to developer sources close to the company. Microsoft officials would not comment on the Longhorn reference implementation.

Does everybody need/want a supercomputer in the home? I'm quite happy with my 700MHz laptop. I just upgraded my RAM to 256k earlier this year. I seem to be one of the few people left who uses computers for computation -- solving scientific problems. It is amazing to me that "average" users need so much more power for office and entertainment use.