Over at Greyhawkery, Mike Bridges makes the point that, from the standpoint of a "modern" reboot, the World of Greyhawk setting is something of a mess. It's a patchwork of different sources, including entire campaign settings ported into Oerth; from Gary Gygax, to Rob Kuntz, to Frank Mentzer, to François Marcela-Froideval, to Len Lakofka, to Andre Norton's Quag Keep novels.
Sometimes the written sources conflict; the aforementioned Quag Keep novels bear little resemblance to the Greyhawk we know, and both Marcela-Froideval's Chroniques de la Lune Noire and Gygax's own "Gord the Rogue" novels featured the world being destroyed, and "Gord the Rogue" had a completely different City of Greyhawk than the published boxed set (for that matter, so did the novel Nightwatch). Castle Zagyg was completely different than Greyhawk Ruins which was completely different than Castle Greyhawk. The adventure "Fate of Istus" module had big mechanical changes happen to the setting that were later pretty much ignored, like monks losing all of their abilities. Don't even get me started on the Greyhawk presented in the three Rose Estes novels. Stop being so worried about continuity and canon. Roll with it.
It also has heavy doses of non-fantasy elements like spaceships (Expedition to the Barrier Peaks, gates to the Starship Warden from Metamorphosis Alpha), the wild west (Murlynd the quasi-deity), and "modern day"/science fiction (the "Factory Level" beneath Castle Greyhawk).
Later published incarnations tended to play down those elements, in favor of making Greyhawk a more "straight" fantasy setting. But I think that approach was an enormous mistake, and one that, should an adaption of the setting be in the cards for 5th Edition D&D, should be turned on its head.
If it were up to me (and it's not), I'd embrace the patchwork nature of Greyhawk. I'd hire Frank Mentzer to write up a full treatment of Aquaria and put it across the Solnor Ocean. I'd hire Len Lakofka to do a full-blown campaign book for the Spindrift/Lendore Isles. I'd hire Rob Kuntz to finally produce a definitive version of Maure Castle. I'd hire François Marcela-Froideval to do a sourcebook for the Empire of Lhynn and use it to invigorate the whole region of westernmost Oerik that was detailed in the Chainmail game. Go wild. Invite, nay, insist, that every author bring his or her unique voice to their region.
One of the complaints about Greyhawk has been that it's too generic. Too vanilla. This would be a way to make it stand out from the Forgotten Realms in a big way. If anything, FR is the setting that's homogeneous and High Fantasy Medieval. Greyhawk's big claim to fame is precisely its kitchen sink approach when it comes not only to genre, but to authorial voice. That should, and could, be its strength. There's an adventure with King Kong, fer crissakes. Go gonzo with it!