This would be a delight! I think it'd be satisfying if HOTD can pull this off well. If it works, i'd be a feat similar to the Hooded Justice reveal in HBO's Watchmen series.

I'm with you up until Laenor returns ten years down the line. IMO it'd be a missed opportunity to develop Addam, since I think the ambiguity of his past could complement Laenor's escape.

In F&B, since Addam was (falsely) believed to have been Laenor's bastard and was more likely Corlys' son, I think the show could take liberties with why Addam was able to bond with Seasmoke.

We know 10 years will pass in between Laenor's (staged) death and Addam claiming Seasmoke. Even with the fakeout death, I think Laenor will die before Seasmoke allows Addam to ride him.

I could see HOTD fleshing out Addam's past to hint that at some point during those 10 years, Laenor crossed paths with Addam. Perhaps Laenor and Addam commisserate on having Corlys as a father? (They gotta set up that eventual backdoor pilot for Corlys' prequel somehow!)

Perhaps Laenor actually assumes some sort of fatherly role to Addam? Maybe shows him how to ride a dragon? Thematically, it could be a neat parallel to Daemon's ambiguous relationship with Nettles. (I choose to believe he treated her like a daughter.) It ties into the overall "history does not remember blood, it remembers names" theme.