How do you bring out the critical thinking when it has been conditioned to the back of your brain?
I think the main thing keeping the critical thinking in the back of their brain is that they stand to lose too much if they question the teachings. If the religion announced today that the new understanding was that non-Witnesses could survive Armageddon, and there was be no more shunning of those who leave, people would start thinking critically about the religion tomorrow!
Now, some would stay in because they would be afraid of others' disapproval, or of losing the paradise hope, or of losing a belief in God, but many JWs who didn't seem capable of thinking would suddenly seem to get a lot smarter overnight. That's my prediction, anyway.