Actually, if you have some time on your hands, you could check the CCC talks from 1-2 years before Snowden leaks and after. A lot of things were suspected for a while. Then comes Snowden, essentially saying "yup, and more".

Then next CCC: "hey, now all of these things are confirmed!" (And it's worse than our worst nightmare.)

IIRC, the huge data centre in Bluffdale, Utah was one such thing that was identified quite early.

media.ccc.de