It's not a big deal. As the tablet matures eventually you'll just be able to connect a usb/bluetooth keyboard to one, when necessary.
That is, one dock connection that supplies power, feeds an HDMI display and connects a keyboard, transforming the ipad screen into a sort of oversized trackpad. optionally with some context sensitive controls.
With that, when people want a more traditional computing experience, they just carry their device over to the desk, dock and get on with it.
The only real missing part is OS-wide awareness of such a dock, so that the UI can shift to being more keyboard-friendly [1]. I believe even the existing dock API could effect this on a smaller scale [2] if Apple greenlit a third party to build one.
[1] Using a bluetooth keyboard with the iPad is pretty weak, due to the lack of consistent navigation support. e.g. alt-tab/cmd-tab sorts of behaviors, arrowing through pick-lists, universal tab/shift-tab support, etc.
[2] Each app would have to look for said dock (and not just on startup) and the OS still wouldn't be integrated, which would limit things a bit.
I don't think making the iPad a trackpad for an external display would work well, however, since the iPad does not have a cursor and the GUI is not designed to be used with one (try the iPhone/iPad simulator on a Mac to see how it works). Making it work as a 1-1 mapping from the iPad to the external display is what the current HDMI connector gives you anyway.
The thrust of my wonder about a possible docking solution was towards a real, actually good, option.