Don't forget corporations and individuals. And of course blackmail. That could be very profitable, specially against powerful people, politicians...
If they didn't have segregated access (and it does not appear that they did) then that would have surely been too juicy to pass up. 20,000 documents is a lot.
This might also go some way to explaining the panic, if they don't know what he's got and he's had access to data like that then some people must really not be sleeping well right now.
It's safe to assume that most (every?) politicians data is part of NSA's haul. Add journalists.
I find the debate about surveillance terribly naive. Politicians get corrupted as soon as there's no one closely looking.
Creating such a surveillance and secret-keeping mammoth is calling for massive corruption. And this thing has been running for years.
Some would like them to remain thieves after they've done their thing and I'm sure that some thieves eventually consider becoming whistleblower but in the interval between taking the data and exposing it there is no real difference that you could outwardly discern between the two cases.
Is an assumption on Schneier's part. For all we know there were dozens or more. They may not have released the data or they may have sold it to some foreign agency instead.