There is a long list of legit and or cook reasons to have a microchip in a brain. Controlling or assisting damaged brain structures, you can mitigate the symptoms.of Parkinsons, give vision to a blind person.. but I also think the cool parts van be nice and probably are inevitable. Being able to communicate in your head, that sort of thing. I see it as something that will happen and people WILL do it.
Also, who do you think will make these chips? A fairy? Of course companies will (and already do) make them.
I think instead of screaming NONONO we should start thinking about what rules your any such companies to follow. Maybe have the design schematics be open source. A hard "off" button, somehow. A ban on ads and tracking (in combination with the hard off)
Yeah there are very start things possible, doesn't mean it has to be like that