Fundamentally the Snowden relations haven't lead to serious legal or operational change. Why is that? Because knowing all the technical information about PRISM etc is interesting for techies but it hasn't resonated with policymakers. They act on personal interests and those personal interests are dictated by a fear of looking soft on terrorism, crime or child porn etc.
So in theory what should a new Edward Snowden do in the future in make policy change?
Well having worked in Westminster Parliament, I think (if possible) he should release one month's worth of communications (email, SMS, web history) between MPs or House Members/Senators in the USA..
Why? Because that will change the personal risk calculous for policymakers. Without wanting to be crude, if you have ever worked in a parliament, a huge chunk of parliamentarians have something to hide - they are fucking someone else, they do coke like it's going out of fashion, they vote against things when they secretly do it themselves etc.
Parliamentarians always write bills with added protection for themselves which their citizens are not privy too (the Wilson Rule in the UK for example). Now at times that privilege is important (e.g speaking rights without threat of libel etc) but often it serves parliament to pass laws safe in the knowledge that they won't be subject to them.
Think I'm being ridiculous? Maybe I am, but remember what happened with the Senate Intelligence Committee over Snowden revelations (not much) and compare that to what happened when the CIA got caught spying on the Senate and interfering with the route report (people got torn a new asshole). That's because the US parliamentarians suddenly felt the same sense of violating that they were happy to allow citizens to be targeted by.
...anyway this is just a thought experiment but happy for others to point other ridiculous ideas - cos change is getting further away than ever.