I'm calling it right now, actually my coworker called it but he doesn't post here so I'm taking the credit:
That kid is Jack's son.
The show was bothering me recently because of the lunacy of some of the things it tries to pull off. It bothered me because there still was this faint line that tried to anchor it down in reality. That line has broken, and so now I'm not so bothered. Bring on the craziness!