I actually think Snowden's documents support a cautious optimism about Tor.
The techniques they detail all amount to an admission that Tor itself is still quite difficult for the NSA to de-anonymize at scale. They resort to exploits against browsers instead, which is far less scalable and far more risky.
According to Snowden, the NSA doesn't want to waste valuable vulnerabilities on low-value targets (since this risks discovery and disclosure, making the vulnerability useless in the future).
So they can't do mass surveillance of Tor, and can only de-anonymize targeted individuals under optimal conditions.
The techniques they detail all amount to an admission that Tor itself is still quite difficult for the NSA to de-anonymize at scale. They resort to exploits against browsers instead, which is far less scalable and far more risky.
According to Snowden, the NSA doesn't want to waste valuable vulnerabilities on low-value targets (since this risks discovery and disclosure, making the vulnerability useless in the future).
So they can't do mass surveillance of Tor, and can only de-anonymize targeted individuals under optimal conditions.