PDF magazines may be used to compliment the WTS publishing work, but that ceartainly doesn't meant that printed magazines are on their way out.
I could be wrong, but I believe they actually still produce hard copies of the material currently available online (mp3 files). The idea of using the web is to cut down on the costs of tangible media, not to eliminate it. Not all JWs have internet access, printers, mp3 players, ect. Do some of you reall believe that pdf files will be it? What about older people who can't use a computer? The idea of a totally digital Watchtower is abusd. They will simple use it to cut costs where they can, and that's about it.
As for 'tracking' members IP address I think the imagination on this board is astounding. The WTS doesn't care that much. Sure, if something is obvious (active member owning a ex-jw/anti-jw website) something could (I stress COULD) happen. But the amount of resources necessary to mine the kind of data people are talking about here would be huge.
The main thrust of the WTS/JW agenda is focused around information found in printed magazines, and it will remain that way for a long time to come. The Elders in local congregations will continue to be the tool used to control the flock. My guess is the magazines will go live in pdf with no security barriers. It would simply be too complicated to implement. The only people that have an interest in the PDF files besides JWs are ex-jws, and the WTS has already shown that their intersts in the activities of ex-members is nominal at best.
Additionally, to believe that there will be some paradigm shift away from this model is to ignore 100 years of watchtower history.