I don't know about that. Dark Sun was an underperforming setting in the TSR 2E era. That doesn't mean it did not have its fans and followers - but it never had an iconic status in the D&D mythos in terms of "ZOMG!!!!111!! You can't mess with THIS".
I think it's fair to permit the designers their ability to put their own stamp on the gameworld in the 4E books to be released. It's been nearly 20 years since the release of the initial Dark Sun boxed set. There is nothing to say that Tim Brown and Troy Denning recieved some wisdom from on high that was inscribed on great stone tablets that Rodney Thompson must respect for all time and never trample upon.
Well, heck, I'd be okay with them creating an all-new history for Athas... as long as it didn't, in my extremely prejudiced and idiosyncratic opinion, suck.

But then, my position on Athas's original history is firmly in the "loathe" camp. I argue for a "tabula rasa" setting mainly on the grounds that a) that's a solution that accommodates both lovers and haters of the original storyline, and b) it's totally thematically appropriate. In a world with such ruthless disregard for anything but the bare necessities of survival, who has time to write histories? Let it be a mystery to the players, to be created and revealed by the DM or not as he or she sees fit. If the DM doesn't want to make up a history for Athas, then it's simply lost for good--only the sorceror-kings and the Dragon know, and they're not telling.
The only history I need is "The natural world was shot in the face, the Sorcerer-Kings have ruled for generations..."
That's pretty much all I need. There's no need for fey* to ever have existed. (Fantasy kitchen sink settings are a pet peeve of mine, which is one of the reasons the original backstory cheesed me off so bad. Here we have a setting which doesn't feel the need to incorporate every tired old D&D trope... but then, as soon as they start creating a history for it, they have to go and cram them all back in! What, you just can't wrap your head around the idea that NOT EVERY FANTASY WORLD HAS FREAKING GNOMES?!?)
(...Er. Sorry. Got a little worked up there...)
[size=-2]*Giants do exist in Athas. Or at least they did last time I checked. They go wading in the Silt Sea and some of them have animal heads.[/size]
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