What I really want is to use the Rasperry Pi as both a computer system and a throw away embedded module.

So I would want something like this when I program the Rasperry Pi to say control a robotic arm somewhere. Then I want to be able to pull the rasperry pi out of this tablet and actually place it in the robotic arm module.

So if I have several projects going on like auto fish feeder and / or auto plant waterer.... I want to be able to bring the tablet around attach the rasperry pi to it too make changes.

While the demo looks like this is what is happening I'm assuming that the final product is basically like a phone, the pi is eternally stuck inside the tablet?

$200 is too much for something like a auto plant waterer but $30 for the pi is perfect for this. Therefore make the tablet interface a module to the pi. That's the whole point right? Otherwise why use the pi over my phone? there's no point.