I think the only thing that would truly bring the 1914 doctrine to rest would be for the Jehovah's Witnesses as a culture to become more educated than they are. I am talking formally and informally educated. It doesn't take a college degree to read about and understand when Jerusalem was destroyed. Without 607 BCE, their 1914 doctrine crumbles to dust.
Imagine a group of well educated governing body members* sitting around the table and realizing their entire religion contradicts archaeological, historical, and scientific facts.**
* This will never happen.
**This will never happen, either.