In the “Young Sheldon” finale, we see Amy and Sheldon sometime in the future, though it’s not made clear exactly how much time has passed. The show has used Parson’s narration as the older Sheldon throughout the series (and even had Bialik do voiceover for an earlier episode), so it was a great way to finish things out. Still, it was odd that Leonard was never mentioned throughout. Sure, Leonard and Sheldon met after the events of “Young Sheldon,” but Simon Helberg’s Howard, another member of the friend group, appeared in season 5, and there’s plenty of mention of Amy, whom Sheldon didn’t meet until later either.
The majority of the concern around Leonard’s whereabouts, however, comes from discussion of Amy and Sheldon’s children, particularly their older son and younger daughter. Amy tells her husband that their daughter is interested in acting, which Sheldon isn’t impressed with, telling her, “I told you we never should have let Penny babysit.”
Penny (played by Kaley Cuoco), was Leonard’s wife at the end of “The Big Bang Theory” (and is the show’s most likable character to boot). There’s no reason why Sheldon wouldn’t say “Leonard and Penny” if they weren’t both babysitting, and why would Penny babysit alone unless she was now single either because Leonard died or he and Penny got divorced? The other major clue was that Amy and Sheldon decided to name their son Leonard, which has some interesting implications.