This is one poll where I really needed the "other" option.
Greyhawk is sub-optimally supported and not dead, but it should be. Don't get me wrong -- I really liked Gygax's creation.
It's not that anymore, though. At this point, there is no way to turn out a version of the setting that would please enough of the die-hards to be profitable or sustainable.
The beauty of 1E Greyhawk wasn't in any particular genius in the design of the setting, though it was well done. The lure was in EGG's writing style and the way he used the Greyhawk flavor to make the 1E books come to life. 1E AD&D had an implied setting that was neither too distant, nor too dominant. Part of that balance came from the non-advancing timeline, archetypal concepts, and historical feel of the writing. You could not do the same thing with either FR (timeline advances and often requires too much backstory) or Eberron (too alien and too much backstory).
Greyhawk didn't work as the implied setting for 3E for several reasons. One is that there was legacy ideas that didn't translate well. Take Wee Jas, for example. In the 3E PHB and based on the default rules for undead, Wee Jas made a lot of sense for necromancers (divine or arcane), but the grognards knew that she hated undead. That's too much for a one-off in the PHB for a generic deity.
Another is the writing style used. The Knight Protector of the Great Kingdom class was pretty generic and easily adapted to another setting. Although there was mention of the Great Kingdom, there wasn't anything actually interesting or compelling to it. It just didn't resonate. EGG had a way of dropping a couple of tidbits that didn't take up much space, but sucked you into another world. The Binder section of Tome of Magic is the closest I can think of in 3E, though there was some posibility in the Tome of Battle, too. Though neither really measured up, I hope WotC continues to try in 4E.
Greyhawk should be left to die. I hope there is no 4E version. I hope they don't license it out. If it does happen, I want to see the 1983 box updated and nothing more. Just give the 1E or earlier grognards a way to use the new rules in the old setting.
What I'd rather see is WotC come up with a new implied setting for 4E. Not a setting search or anything hard and fast (at least at first). Just open up the option for writers to add a bit of fluff to their rules descriptions in a way that doesn't involve repeated use of the "iconics" or saying, "for example". The back story for the Duskblade is a good example, too, though I'm not a fan of that particular class. If people get really interested in the implied setting, then WotC can organize it and publish it just before rolling to 5E or in 2013, whichever.
