On a personal PC level:
The market for the home computer
is at a stage in my experience where as laptops do drop in price they are commonly replacing the desktop. I have found that the general public is really excited about the idea of being able to carry the computer
to the porch or in front of the TV.
This day is here. The lower spec Dell laptops can be purchased for 499$ US all year long now. They are still nothing fancy, yet for a personal computer they still get the job done.
On a business PC level:
The desktop PC in the business market is slowly being migrated to laptops so that productivity can be achieved when traveling or away from the desk. *That is how I am online posting this currently.* Yet there are still some application and scenarios that I do not see a laptop prevailing for years to come. CAD operators for instance would shoot me if I were to tell them that they had to stare at the poor quality of a laptop screen to do their work. For office use the quality is quite nice and even better now with the WXGA screens however when the pixel resolution for CAD and or graphic art
is broken down you will still not get near the resolution that you could achieve from a true flat CRT. Theft also becomes more of a concern for business owners as laptops are much easier for an upset employee to either break or forget to return when they are fired.
**Laptops are the coming age and will without a doubt replace the desktop computer
in the years to come. I do believe however that we can look forward to many more years before this migration to portability is complete. I estimate 2014 will be about the last desktop PC's to be seen.