I think the tablets will definitely replace tradition laptops, the question is just a matter of time. In fact, for me personally, my IT has almost replace my laptop 100%, in my mind there are only two things that make my IT fall short, 1) storage capacity and 2) software library.

However I predict that in 5-10 years, devices like the internet tablets and UMPC-type devices will have replaced traditional laptops in at least 75% or more of marketshare. (note that I'm talking about MOBILE marketshare. Just by the limitation of the screen-size, they'll never fully replace laptops in the home or desktops, etc) In my mind the only things left for the ITs before they can completely replace laptops is:

- Self-sufficiency: for example ability to update OS without need for secondary "real" computer, for example.
- Out of box printer support
- Large (both free and commercial) software collection for a wide audience with diverse needs
- More powerful core hardware (for example to allow smooth playback of large H264 files like on the iPod)
- More storage capacity at a reasonable price (say 64GB for $100) more of an issue for the N810

And most importantly: Ubiquitous internet connectivity without requiring any external hardware (i.e. mobile phone). Hopefully this will be closer to a reality when the WiMax tablet it available and will become more and more true as WiMax is widely deloyed and available virtually anywhere.