Any post within a quarter is still valid in my view
I do like the idea, but I think you could make it viable If you take the survival part out of it, change parasites with bio enhancements or cybernetic possibilities and it would work on a global scale. Also you can use parasitical forms to implement some fun stuff, like Dax in startrek stuff. Also, slaves will probably be not done in the curent political environment, but If you plase the aliens differently, or add domesticated animals that can do stuff to help. It is also different, robotic work force that you need to program yourself and provide with docking stations/ energy units.