As with most iPad uses/setups this is perhaps extreme speculation. However based on the various Remote Desktop and Virtual Network Computing (VNC) options that are available to the iPod/iPhone I see the possible return of terminal style computing. In my experience with my iPod Touch and JaaduVNC (as well as RemoteTap) a setup that uses a MacMini (or any PC) as a central server with iPads connecting to it could be a viable household alternative to giving everyone in the family their own computer or laptop. This requires several bits of software to execute in a practical form.
First is VNC or Remote Desktop applications being allowed on the iPad. I do hope Apple does not banish these programs from the iPad's Apps Store. Remote Desktop and computer control seem like a perfect way to expand the iPad's utility in ways the device along can't handle.
Second multiple user desktop remote access. I am not familiar with the Windows options but I did find Testplant.com's VineServer of the OSX side. I have not tested it as yet but it looks like what is needed.
This really hinges on how well the iPad A4 processor can handle the decompression and rendering lag needed for VNC use. If the iPad can handle such Remote Desktop use, Apple would be foolish IMO not to look at supporting this kind activity in OSX proper (as there are technical issues in running multiple users at once), especially if they market it for use on something like a household MacPro or other powerhouse Mac.