I would like something new, but I don't think that's happening. It's risky. It's not the right time. It's early in 4e's life cycle (save the new stuff for when you want to revitalize sales!). 4e is still kind of struggling to win over fans of earlier editions.
So the best bet is to revive something fondly recalled in a way that does justice to the old material, but captures some of the best features of 4e at their most vital.
Dark Sun would have trouble doing that, for reasons I've elaborated on elsewhere (conflicting philosophies).
Dragonlance wouldn't have as much trouble, but most of the "hints" for DL have been since shown to not be about DL at all, necessarily.
I also think there's a chance for an outside contender in Greyhawk. There hasn't been real bad buzz about going back to a "Gygaxian" Greyhawk, and the world would easily show that you can do "old school" in 4e. Greyhawk also has the advantage of having lain fallow for longer than DL has.
Since I can't bring myself to vote for DS, even with it being a potential contender (because I forsee it being the straw that breaks the camel's back for me with 4e)....
...and since DL has been shown to be in other things...
...I will tentatively place a bet on Greyhawk.
Of course, if we were betting actual money, I would wager on Dark Sun. Not because it's likely, but because then it's win-win for me. If it doesn't happen, I'm out some money, but hey, no Dark Sun yet! If it does happen, well, they might FUBAR it, but at least I'll have your money to console me.
And then, if they don't FUBAR it...DOUBLE SCORE!
But for fun, I'm going with the outside chance. Honestly, there's not much strong evidence for ANY setting at this point, which I'm sure delights the WotC folks to no end to see us grasping at straws.
