So, I'm going to preface this with a simple statement: I don't like Dark Sun. At least, the way it was sold to me in the 90's. The 90's version of Dark Sun did not feel like D&D to me, and the play loop for the setting that I saw was "make the most OP character you can and watch them die of thirst".
That said, what is being presented here might convince me otherwise.
What would sell it for me is the idea that Athas isn't a doomed planet; it can get better. Maybe not restored to former glory, but things can get better. The sorcerer-kings can be overthrown. Slavery and fascism aren't the only type of society. Metal and water aren't completely gone. There is something worth fighting for.
As someone who isn't wedded to the intricacies of the setting, I am not against changing things to make them work better with D&D. I much preferred 4e's presentation of DS than 2e's. An Oath of Glory paladin absolutely feels on vibe. And in a conflict between fidelity to 30-year-old sourcebooks and making the setting playable with the 2024, I will choose the latter every time.
But absolutely moving the vibe from "survive in a world near death" to "save a world on the verge of extinction" would be a big step to making the setting appealing for me.