I believe we are there now with the NSA Utah data center, it is well known that the servers there are able to hold all data in the world for five years. They are able to hold around the thousands of zettabytes or yottabytes and there Computer capabilities is Cray XC30 Supercomputers will serve the facility, running up to 1 million Intel Xenon core processors at the same time as fast as 100 petaflops.
So I do think you maybe underestimating what the NSA can do right now. Also remember this is only Utah data center, NSA has data centers all over the world. Maybe not as big but when you put the rest all together it is about another Utah data center.
I am just saying when the time comes we all need to go hunting for these towers and cameras.