8 miles away, if cities, now that would be impressive beyond belief. 8 miles away, small town on the side of a hill, sure.
Though a drone 8 miles up, would we see or hear that?
Also are the NSA as curtailed about legal transmit power as as mear citizens? As being able to boost transmit power, yes 8 miles reasonably focused and drowning out everybody else, would not be subtle.
Now when they can do it with low-orbit satellites, an array of those beamforming - oh it maybe fantasy, but gets me onto one safeguard.
Should wifi have radio latency checks? By that, ringfence via radio latency how far away somebody can connect - even if they can see or transmit from 8 miles away, if you had protection that ignored anything over 20 meters away, you would totally be able to lock those connections down.
That would need to be at chipset level, though with a good resolution ping, you could augment security and with a more granular ping, would be able to tell how far away any connected wifi device is. So technically possible with hardware already and just a software feature that could be added and remove anybody over a certain distance from even holding a connection upon the network over wifi.