Slow typers with little volume of input can make it work. But if you look around you at conferences or other venues when people are away from their desktops, you often can see that tablets are one more device to carry around, as people now have their notebooks, their smart phone and now a tablet with them.
There will, over time, be more changes in both tablet and PC spaces, to try and blend the two functions of "content creation" and "content consumption." In some, perhaps many cases, it might even work. If you think about a "dockable tablet" or a one-pound notebook, you get the likely trajectory.
What Needs To Happen For Tablets To Replace Laptops?