Not really. Greyhawk has an even older fanbase than the 2E favorites like Dark Sun and Planescape. With the older guard mostly going into the OSR or sticking with AD&D, there’s really no draw for standalone setting books that will sell to a fraction of a fraction of a fraction of their audience.
The tier rankings that WotC survey revealed are likely what we’ll get. Tier 1 and some/most/maybe all of tier 2. Anything else will be bundled or left on the cutting room floor. We might get an anthology with one adventure in each of the tier 3 settings. Or a multiverse book that treats each setting like a Domain of Dread with a quick few page write-up. Here’s to hoping Mystara gets more than a paragraph.