Great analogy. Unless tablets grow in terms of connectable peripherals, I can't imagine secretaries, programmers, accountants, or anybody else spend 8 hours staring down their desk on a 7" screen poking fingers at a virtual keyboard.
Connecting to peripherals is irrelevant in the tablet takeover. In fact, tablets are irrelevant in the tablet takeover. What's going to happen is that the tablet OS and app ecosystem will reign while the form factor becomes whatever is convenient for the task at hand.
Media consumption? Tablet. Work? Unknown form factor, but with correct input/output attached and running the same software as the media tablet.
Things is, what platform is going to be the best at switching modes between desktop and tablet, with full support for multiple monitors, printing, VPN etc, stuff business will like? Windows 8.
Maybe it's better the way it is. Maybe having a machine for "work" and machine for "play" is how we keep things intuitive, modular, and clean.