To move away from the oft-productive topic of food metaphors for a second, let me ask some questions:
1) What specific elements of Greyhawk would need to be maintained to capture the idea of being "respectful to tradition"?
2) What elements of 5e could be introduced into Greyhawk in a way that respects the Greyhawk tradition? What elements would specifically need to be excluded?
3) What novel concepts could be added to Greyhawk that both enhance the Greyhawk flavor and add to the 5e experience?
I cannot speak for everyone, but for myself- this isn't easy; because there isn't a single aspect that is dispositive. It really isn't about complete fidelity, as much as the gestalt.
To use the dragonborn example that always comes up. Dragonborn, in my opinion, are not native to the Flanaess. If the 5e version of Greyhawk just ignored that issue or retconned them into the existing area, I would be angry- because that would show a lack of care in dealing with a fundamental distinction, and a lack of respect for the setting.
But the issue isn't dragonborn. If someone took the time to either integrate them in a meaningful way into the setting or to provide a quick sidebar as to how "non-native Dragonborn" could be used, I would have no issue with that, even if they were just a "rumored Kingdom to the east."
It speaks to the deeper issue, thought, of what the "gestalt" of the setting is. Some of the aspects of Greyhawk that can be played up (but not all) would be:
A. Humanocentric
B. Swords & Sorcery (think Conan if you don't have a background, not LoTR).
C. Gritty
D. "Low Magic" (to acknowledge what
@Minigiant wrote, GH isn't low magic per se, as it is kind of the opposite of Eberron in some ways; magic is rare, but what magic there is can be very powerful.)
E. "Grey" morality. This is the whole, "Good nations can fight each other, neutral is a balance, evil often triumphs," sort of thing.
F. Last points of light of civilization holding on (a somewhat post-apocalyptic vibe), with decaying greatness (Great Kingdom).
.... there's more. The point is, I want a product that really goes hard into some aspect, or aspects, of this setting, while re-introducing today's gamers to some of the legends of the past (the artifacts, the names, the places, the crazy Nazi monks, and so on).