I dislike the premise behind "it's all encrypted and we cannot do that anymore" since we have no idea what capabilities an agency like NSA has now or could have in the future. If their capabilities grow perhaps they can replay all that saved encrypted data from their Utah Data Center and throw it into AI for analysis. Why do you assume a human has to be involved in the judgement process for it to be taking place?
I don't. A human is not necessary to the process. A human is necessary for the process to be done well. And if the NSA has broken its own encryption, to the extent that it can read past traffic, call the IMU because there are some Field's medals that need handing out.
The UK equivalent of the NSA invented both RSA encryption and DH key exchange years before any of Diffie, Hellman, Rivest, Shamir, or Adleman did their work. No Fields medal per se, but two Turing awards...
I think the odds that the largest employer of mathematicians in the world is secretly sitting on ground breaking fundamental math is pretty high.
That will still happen, but it will happen _after_ AI processes ${HUGE_NUMBER} of data streams simultaneously to pick out the interesting ones. Human intelligence and AI are complementary in this regard. We are better at the fine detail. They are better at the raw throughput and parallelism. Both types of brain working together to spy on you should terrify you.
Current theory isn't about missing connections between people. With social networks big and small, everyone can be connected to everyone else. Thanks to twitter I'd bet the US president isn't more than a hop or two from every terrorist suspect on the planet. (Not trying to be political, making a point about connected people.)
So the existence of "links" no longer matter as there are links between everyone. What matters is the quality and content of those links. It starts with bi-directionality. Sure, the president's twitter feed is read by terrorists but do they also speak back to him? Then does he reply? That back-and-forth would represent a higher-order of connection. Are they speaking publicly? How many people are in on these conversations? A private conversation matters more than a public back-and-forth twitter war.
A machine mining a database for raw connections isn't useful. To judge the quality of connections you really do need a human mind capable of making a judgement call. They need to put the connection into context. Or, since it's all encrypted and they cannot do that anymore, everyone is linked to everyone. A warrant can be got for anyone anywhere. Send in the killbots when and where the boss wants.