My husband came to a large dinner at my new church about 6 months after we left, and said he couldn't believe there could be so many decent people under one roof.
i think many witnesses secretly believe many more people than just witnesses would be saved at Armageddon, they know them from work, and school, KNOW they are good people. I've heard some elders privately say this...very privately, and only if they completely trust you.
If jws disappeared, there would be no affect on the world, not really. People who like a lot of rules would join Church of God or something. But guess what...a whole lot of families would be back together.