There’s a lot of stuff that this show could do that could in theory strengthen the OT.
For example, we could get Obi-wan meeting Vader in a scene reminiscent of Luke meeting Vader in ROTJ where Obi-wan tries to convince Anakin to turn away from the Emperor. That way Vader’s line ‘Obi-wan once thought as you do’ would make more sense.
A fight between Vader and Obi-wan could lead to Obi-wan escaping in a way that implies that he is killed. That way the situation in ANH, where everyone assumes Obi-wan is dead, makes more sense. Similarly, we could see Vader recognize Obi-wan through the Force, as he states in ANH.
We could get a non-silly explanation for why Vader never bothered checking Tatooine for Obi-wan or potential progeny. We could see, perhaps via flashback, that Vader has visited the tomb of Padme on Naboo, and seen that there is a small tomb beside hers, unnamed. Perhaps he demands of the official who interred them if there is truly a child buried here, and they swear on their life that it is true. He believes this and in this place finally gives up his last hope for redemption.
Obi-wan’s mission off-planet could be due to a belief that he can still do good in the galaxy and right some wrong. The end of this mission may have him realize that he is indeed becoming too old and too weary to continue the fight, recognizing that perhaps his idealism of youth was merely a zealous crusade, confirmed by the bitter denunciations of Owen and those who blame the Jedi for allowing this Empire to succeed.
While I hope that something like this comes to pass, I have absolutely no evidence based on this trailer that the show will deliver on any of this nuance. My expectations are in the Sarlacc, but hey, the show could surprise me.