That point will always be a temporary point for some users. Software will continue to push the hardware. For home use, browsing the internet, running MS Office, any contemporary processor reasonably close to 2 GHz will probably do for awhile, but other types of software will continue to suck in the CPU power.
Seven years ago I had AMD machines at home and at work. Running AutoCAD the AMD machine was like a rocket. But now we have gone from Win98 to WinXP, from AutoCAD2000 to Autocad2009, plus third party add-ins, and gone to a newer generation of AMD processor, and those machines are so severely underpowered that it is very frustrating to try to use them. We can go to overclocked dual core and quad core processors that will be about 4 times as powerful, and get ahead of the software requirements temporarily. But if we go to Vista or W7, and now we are going from AutoCAD to Revit, so in a few years even the fastest i7 will still be a dog. (We put more demands on the CPU than Crysis ever will.)
For gaming the upper level of contemporary processors seem to do OK, paired with appropriate GPU's, but games will grow in requirements as well. I remember when we used to play Descent at work, on 486DX-40 processors. Modern games have not increased the range of movements beyond Descent, but they have increased the detail of the graphics by a lot, and the CPU requirements as well. It is easily possible to build machines with dual core and quad core processors in the near-4 GHz range for gaming, probably 200-500 times the power of the 486DX-40 in a single core, and still struggle to play the game as fast as the 486 would play Descent with its low-res graphics of the day.