Sadly, even after Picard season 3 this mystery is still unsolved.

Serious answer. TNG has a lot of shit like this. Leftover plot hooks that completely lack follow-up. Far too many to wrap up in one season of modern prestige TV.
It's just how TV was back then. You wrap the story up in 45 mins. Maybe some things get revisited, if the writers and producers don't forget about them and the actor is available. Serialized stories were the exception not the rule back then.
Honestly I feel like this makes the Star Trek universe seem bigger. Every character has a lot going on and not everything that happens to them revolves around one storyline. There's a whole galaxy out there full of things constantly happening! A lot of these would be followed up in books. Iirc it's mentioned in one that Worf and Jeremy exchange letters regularly and he does visit on occasion. We just accept that this happens off-screen because Worf has a life beyond the brief glimpses into it we see. Modern TV is too tidy, with everything tied to one or two storylines and everything being wrapped up tidily with maybe one or two cliffhangers. It makes fictional settings cough Star Wars cough seem small and insuler.
- This is probs one of the reasons Star Wars always felt like a small galaxy cpompared to Star Trek. Everyone was so easily linked, found and plots tied up that it made it feel small.
- Modern TV is too tidy, with everything tied to one or two storylines and everything being wrapped up tidily with maybe one or two cliffhangers. It makes fictional settings cough Star Wars cough seem small and insuler.
  Well put.
  TV before streaming (notably the last ten years), episodes stood alone. You may get a little continuity in the characters, but not in story arcs.
  This made it all a (as you put it so well) a "glimpse into each character's life", leaving the viewer the opportunity to ponder "what else is/could there be", which I find far more satisfying than having the answer provided for me.
  I must say, I see this as significantly a generational difference (with some personality difference in there too, I know a few boomers who like the tidy story approach).
  
  I agree, but one must also consider the nostalgia element, and that maybe that generational difference can be attributed to that to an extent
- Modern TV is too tidy, with everything tied to one or two storylines and everything being wrapped up tidily with maybe one or two cliffhangers. It makes fictional settings cough Star Wars cough seem small and insuler.
  Interesting point!
  I think a big part of this is because of the internet. Nowadays, if the writing isn't 100% polished you will get people screaming loudly about inconsistencies, plot holes, or hooks left hanging and I'm sure this has an impact on the showrunners.
  That said, I think you can have highly professional/polished writing, and still make the universe seem big and complex. The high quality dramas (Sopranos, etc.) have shown this. Not something Star Trek has every really been good at though.
  
  I think late DS9 and now SNW balance it well enough. You just have to mix episodic and serialized story-telling. I agree on the Internet being a problem though. Can you imagine if something like cinimasins was around nitpicking TNG when it was on air?

Note Jeremy died on his way back to Kronos

Damn Worf. Your adopted son and your son son.
- Dropped the father ball twice, mad respect!
  
  Dropped like a barrel on his fucking spine.

I remember wondering what happened to him but he never came back
- Dang serialized TV where everything has to go back to normal after every episode got to him.
  
  Another reason I never get invested in the romance.

Shh, we dont talk about Jeremy.

I always kinda assumed he probably went back to live with some family members. I don't think the Enterprise is gonna let a kid just live alone in his own apartment.
- Picard barely likes kids being on his ship with families, there's no way he didn't throw him on the first transport back to earth and kept on cruising.

- That was my first thought too!
  The young villian character 'Hob' from Robocop 2
  https://villains.fandom.com/wiki/Hob
  Thank god there are still ancient ones who remember that.
  
  Holy shit, I knew I've seen him somewhere before!!! He was the little drug dealing brat!!!
  Awesome sequel by the way! I don't care if many people give this movie shit, it's great!!

Ad Aster per aspera!
(I'm fairly certain that'll be my best Latin pun of the day.)
- Nice

Didn't he go back to Earth to live with his human relatives? My guess would be that Worf would be his eccentric uncle/cousin who came to town every now and again to take him hunting and tell him war stories. Plus the Rozhenkos are on Earth, so I'd imagine Worf would ask that they keep in touch with him, too. I bet that, aside from the trauma in this episode, he probably had a pleasant and uncomplicated life on Earth, but he could tell kids at school that he was also a member of a Klingon family and they'd have to believe him or else his Klingon crew would have to show up to defend his honor. That would be rad, imo.

Republicans about to show up ranting about a pizza basement on the Enterprise and shit.