Metadata and DPI is still pretty informative.

I will try to exemplify internet cables with a fisherman going into the ocean. The person can take a variety of strategies to achieve their goals, here are a few:

- Fisherman goes to X location because he knows at that time he will be able to catch tuna & mackerels.

- Fisherman goes to a random location capturing whatever he can. He can later decide what is of value or not, whether he will throw it back into the ocean or not is up to the captain.

- Fisherman goes to a random location and captures everything. There seems to be some stuff he doesn't know if it is edible or not, but it doesn't matter. He can store the catch and see if he can cook it later.

Some of the catches will spoil before you are able to figure out whether it is edible or not, others can be useful decades later.

What could someone do if they were to store all the encrypted data and then wait for quantum computing to make the data usable?.. you could target certain streams of data, from certain periods of time, build a case and then decide on the next course of action (target for more data or take physical action.)