I recall the following:
1. I was dating someone who was having conversations with JW's.
2. No one I spoke to at work really seemed to know anything, so I decided to go as an observer with my gf.
3. After observing them for about 6 months it became clear to me that THEY believed it.
If #1 and #2 hadn't taken place I wouldn't have become one. I remember years before when I was in high school someone trying to give me a mag at the door and I asked them to just tell me what was in the mag so we could discuss it. They couldn't so I told them that it didn't seem reasonable that I should bother reading a mag that they'd not bothered to read and that they should go away, read it and then come back so we could talk. (they were about my age).
#3 was critical. If it hadn't appeared to me that the average JW believed it, I wouldn't have become one.
Today, I don't see those factors coming together any more.
In the absence of those, I'm certain this religion will die slowly, or mutate and become as redundant as metrhodists.