@Believe, I also think your parents will be okay. I think this is a good line of reasoning being used with your parents, although I think that a) the bOrg won't have the staying power of the Catholic Church (mostly because the shunning thing will bite them back when it comes to numbers; and b) all "old time" religion is losing its hold on humanity anyway.
Interesting thing, though, if your parents really believe that a lot of JWs would commit suicide if the bOrg goes down. I personally think a lot of JWs would be [secretly] relieved if it did. But the GB has brainwashed a lot of people into thinking "there is no where else to go"..... not that you have to "go" anywhere ..... and your parents must still buy into this belief on some level.
I think things will get better with time. Especially if they start reading books like Bart Ehrman's. A real eye opener, even if you don't agree with all his conclusions.