Firstly, Anna Meyer's Greyhawk maps already exist. ...
No kidding, really? I had no idea.
Of course I already frolicing know about her maps. In her patreon discord channel, she mentioned wanting to do detailed regional maps at 100 ft per pixel resolution.
Instead of pointing me to PDFs that likely every Greyhawk enthusiast already has, take a moment to note the complete absence of a folio detailing Eastfair, or Torrich. Perhaps Ekbir could use a dedicated product.
Quite frankly, nothing is missing to play in any setting right now. Even the various Magic the Gathering worlds are perfectly well ready to set D&D games or campaigns in. There's nothing stopping anyone from playing anywhere at all. The point, which you so willfully ignore, is that those of us who are playing in Greyhawk (and Dark Sun, etc.) would like to use the DMs Guild to share our creations and to support the creative folks who can enrich our games. It's not an issue of something "missing," it is an issue of new quality stuff.
I mean, your whole question of "what is missing to play Greyhawk right now?" is incredibly dismissive, to the point of being asinine. What's missing to play D&D in the Forgotten Realms right now? Do you think there will be more products set there, and do you think that a game in the FR can be enriched by 3rd party products bought from the DM's Guild? How about Ravenloft? Do you think there is any value to the various DM's Guild offerings set there?
I think the more interesting question is "What the hell do you have against people putting Greyhawk material up on the DM's Guild?" You seem to hold the position that Greyhawk should remain forbidden territory on the DM's Guild at the moment, so how about you justify that?
Edit: Here's another question for you: If there is no value to updating and exploring material from the World of Greyhawk, why is it that so much of WotC's D&D 5e product line has been focussed on stealing people, places, and things from Oerth and relocating them to the Forgotten Realms?