Looks like WotC will release official material for new settings next year. Specific settings havent been announced.
http://comicbook.com/gaming/2018/06/04/dungeons-and-dragons-fifth-edition-campaign-settings/
My friends and I helped fund the Kickstarter. I've started a game in Roll20 using using one of their 4E thule adventures (converting to 5e myself) and it's been a blast so far. Players like the narratives over backgrounds and the setting is presented well. The pulp-adventure-Burroughs-Howard...
I've been playing since the early days of 1st edition and my guess is that the desie for a 5E Greyhawk is misplaced nostalgia. There is nothing in Greyhawk that sets it apart from a thousand other vanilla pseudo-euro-medieval campaign settings out there.
WotC should develop one baseline...