I think for this to work you just have to create a shell and a terminal, to have a killer app that your terminal is the paltform for (realizing this is what kept me from ever moving on the idea). But my point is that I think the shell component absolutely must communicate with the terminal component over the tty subsystem using an extension of ANSI Escape Codes, defined in a terminfo page, so that the terminal component is only concerned with how the information is displayed, and not what the information is.