I think places like these won't ever change the masses wholesale. Hopefully they will create a good bit of erosion for the watchtower. I don't think the WT will disappear anytime soon. There are still too many JWs who have too much invested in it to leave. Even some who seriously doubt still stay because they can't be honest with themselves, and just get by on wishful thinking.
I think growth in under-developed countries where people have poor education will account for the WT's future growth. It will continue to decline in the west, where there is good access to information on the net.
It's nice to see new users on here and watch them blossom into fully fledged apostates. it's gratifying to know that at least some people will escape the mind prison. It makes me hopeful for my own family.