Lets try to quantify it this way. If you look at the countries with the greatest growth in the latest yearbook, and somehow figure out their internet saturation, I think that could be telling.
In Cameroon, I was in 3 cities, Douala, Yaounde, and Bamenda. Most people had no computers at all. (I kid you not, electricity and a tv were luxery items) Anyone who wanted to get on the internet had to usually go to these internet cafe's, where you had to prepay and charge by the hour. Money was limited, so anyone on the computer, on the internet, were doing email, news. Yes, they would google Jehovah's Witnesses. But I promise you, there was no time to do any more then a brief glance at what was there.
It is my belief that only those with private internet access really have an opportunity to investigate JW's on the internet. And it is easier to name the countries that do have this, (i.e. cheap internet access) such as USA and Canada. Great Britain. Australia, for example, then those that don't.
Anyway, the countries which have the money that the WTBTS needs to survive are also the countries that have cheap unfettered internet access. Bummer for them.
I don't think the internet will bring down JW's by itself. I do think it has sprung a slow leak that is impossible to fix for the GB.