NSA will simply pwn the endpoint devices of whoever they're really interested in.

I want to believe that. I want to believe that the NSA, while having no respect for the law, does at least care about results. It would make a lot more sense to tap devices of interesting people, than this idea of bulk collection (which leads to just a lot more noise).

And that would be fine. If they have reasonable proof that someone is bad enough to allow this, by all means pwn the targeted hell out of their devices.

It is not foiling targeted attacks, of course. But it might be making a dent on cheap/effortless mass surveillance, which is the main point.