I'm pretty sure the people who thought the world was flat thought that view would NEVER change. I am also certain that the MOST intelligent people in the world are the ones with open minds whose opinions can and do change according to information that becomes available to them. I will let that statement speak for itself.
I can't think of anything my view has completely changed on but I have become a lot more aware of, and tolerant of, things I wasn't before. The childcare one for SAHPs is an example, although I still think there are issues with it relating to availability for working mums (which I believe is more important apart from in the case of health issues).