I've heard the theory more than once that it's possible that desktops may make a slight comeback due to tablet sales cannibalizing laptops to some extent.
With the continual rise of cloud services to sync all our data and user settings, it may make less sense to carry around your world with you with a laptop that can be destroyed by an errant drop or the risk of theft. A tablet may give you 80% of the functionality you need on the road, with a SFF desktop hooked up to a large screen available for you at home/work to seamlessly transfer to when you really need to delve into your work.
Edit: Yikes, old thread!
I see it more as Tablets enabling a certain segment of the market to ditch both laptops and desktops.
I'm just waiting for some enterprising company to come up with a tablet dock that functions as a monitor stand complete with tilt, swivel, and pivot. Hence, once docked you basically have all of your desktop functionality including adjustable monitor stand.
In such a case, the PC hardware install base will decline, but the PC user install base continues to grow. IE - more and more people using PC's but less people with multiple PC's (laptop + desktop).
There's also a unique situation where "if" (big IF still) Windows based tablets take off, that the PC market will shrink while the non Windows tablet market also shrinks.
In other words, there's a possibility that instead of a person having a desktop + laptop + tablet as many do currently, they could just end up with only Windows based tablet. Or someone with just a laptop + tablet could end up with just a Windows based tablet. Obviously there will always be people that require more computing power than a mobile device can bring, but I think for a majority of people a single Windows based tablet could replace all of their computing devices quite easily. A mobile slate, laptop w/keyboard dock, and desktop w/monitor docking station all in one device.
It's also entirely possible that a few years from now, smartphones will be able to run a full blown install of Windows. At which point it could be argued that one device could realistically replace 4 computing devices all in one.
It's still early days and anything can happen.
Regards,
SB