Anyone else get the feeling that the kid is the "original" Observer that the implant tech is based on? As a way to give normal humans his abilities. The tech itself rewrites and changes the brain, which is what gives them their abilities. My guess is that they found the kid, studied his brain and discovered what he could do, so they invented a tech that reconstructs their brains to mimic his brain.
My guess is that "the plan" is a tech that uses the kid. Sicne he's the original Observer, he is in a way linked to all of the Observers as their brains mimic his. They're "on the same wave length", so to speak. So my guess is that the machine does one of two things:
1) Sends out a signal to kill all of the Observers, essentially ending the Observer threat
2) Send out a signal to reconstruct the brains in to a normal human brain, essentially ending the Observer threat
My guess is that it does the second. As seen in the last episode, Donald was no longer an Observer. He probably used himself as a test subject to see if it was possible, and then, with the help of the Observer kid, developed a way to do it on a wider area.