Sadly, I think very dark with tiny points of light is kinda out of fashion. Optimism and radical empathy are starting to become favored over postmodern cynicism with young people. They don’t just want to use fiction to critique systems of oppression, they want to use it to imagine new alternatives. In that light, I could see a modern Dark Sun incorporating elements of solarpunk, perhaps turning the Tyr into an independent commune where through cooperation and judicial use of preservation magic, the free people have managed to revitalize the local ecosystem and become self-sufficient. This could serve as a home base for PCs who fight the servants of the Sorcerer Kings, liberate oppressed people, and spread their preservation efforts across Athas.
Yeah, I mean, I'm not against that per se, but just like radical cynicism (which Gen X seemed to practice - Elder Millennials like me are usually in-between), it limits the stories you can tell and really colours them. Like, I personally really Do Not Want "Becky Chambers' Dark Sun*". There's a time and place for Becky Chambers. It is not, imho, post-apocalyptic Athas. (You could also go with "Station Eleven, Athas")
Ironically I believe the second 2E boxed set back in the '90s had something very much like this going on, and for me it drastically changed the setting, because it recontextualizes it from "there's a terrible problem and no obvious solution, so you're going to need to find one or find a way to live with it" to "there's perfectly good and known solution and it's just a matter of putting it into practice!". It also tends to deprotagonise the players, and make them mere agents of the "new beginnings" people instead of them driving change in the setting, which is like fine, but it's a very different setting if you have that, and it's a very different role. You can get around that a bit but then you start getting into territory which is less optimistic, because you have to make the commune too cowardly to spread the word or the like.
It also puts a lot of weight on the commune or whatever, who are effectively Starfleet or similar in this scenario, and the players have to really buy into their whole deal, or you get another weird conflict, which I don't necessarily thinks works with that sort of Becky Chambers-ish vibe. And it means that organisation is like, in serious danger of ending up written as basically "saviours", which often veers into imperialist/colonialist stuff (again even if you cast it as a "commune" vibe initially - you can't sustain that on a large scale without it starting to look like a cult). Star Trek has struggled with this at times, and I think really only works because people love Starfleet so much at this point.
Like I was running Spire: The City Must Fall a couple of days ago, and part of what makes it work is that whilst the people you are fighting are definitely very bad, the people you work for are also not necessarily stellar, and may well be willing to sacrifice y'all to achieve a mission or the like, which doesn't work with the whole Becky Chambers-y vibe (I use her as example as she's an easy one for optimism and radical empathy).
I do think over time the style will change a bit because of the scaling up into looking like a cult factor.
But yes you nailed my concern, which is that Radiant Citadel team Dark Sun would be "Becky Chambers' Dark Sun". Maybe what I really want is Karl Marx's Dark Sun lol god knows. Or at least Jean Valjean's Dark Sun.
* = I also, to be fair, Do Not Want "Joe Abercrombie's Dark Sun", where there's zero hope and everyone is going to betray you and it's grimdark to the face.