I don't quite agree that they will go down the "snooping on your browsing" route - I don't think it's in their interest to kick people out who could be contributing money simply because they're looking at what they would consider questionable material on the web. DF'ing is mainly used as a fear tactic to keep people in. If they were so interested in finding dirt on and kicking out ones they would call "spiritually weak" then they could easily start going after "faders", which they aren't really doing to any great extent.
I think while it is feasable, the infrastructure needed for such web snooping would outweigh any potential gains that would come from it. Unless they were going to start outright blackmailing people into donating. At the very very worst, they might snoop on those who they are considering inviting into the upper echelons to check they are legitimate, but they already have all that infrastructure at the branch offices which is well known to all there.
The JW.ORG stuff is mostly playing catchup - I think the timing of doing it now is more to do with old GB members dying and it becoming more affordable to run a website.
I do think you have a point about information control though - that's definitely on their agenda.