No real details, other than denying that it will be Spelljammer, but in the latest Spoilers & Swag episode Stewart stated straight up that another hardcover setting book is coming in 2019:
"Nathan Stewart, the senior director of Dungeons & Dragons and Avalon Hill, made the announcement on his monthly "Spoilers & Swag" Twitchcast yesterday. 'Next year for our annual releases I can confirm there will be a setting book,' he said. 'A new setting book. A book that we have not created that is for a D&D setting.'"
I'd speculate, given the Settings mentioned in the recent marketing survey and what is listed in the DMsGuild, that the likely options are from the following, given we got Magic this year and Stewart has previously said they are not working on a new setting right now:
- Dark Sun
- Dragonlance
- Eberron
- Greyhawk
- Planescape
- Ravenloft
https://comicbook.com/gaming/2018/11/03/dungeons-and-dragons-new-campaign-setting-book-2019/
"Nathan Stewart, the senior director of Dungeons & Dragons and Avalon Hill, made the announcement on his monthly "Spoilers & Swag" Twitchcast yesterday. 'Next year for our annual releases I can confirm there will be a setting book,' he said. 'A new setting book. A book that we have not created that is for a D&D setting.'"
I'd speculate, given the Settings mentioned in the recent marketing survey and what is listed in the DMsGuild, that the likely options are from the following, given we got Magic this year and Stewart has previously said they are not working on a new setting right now:
- Dark Sun
- Dragonlance
- Eberron
- Greyhawk
- Planescape
- Ravenloft
https://comicbook.com/gaming/2018/11/03/dungeons-and-dragons-new-campaign-setting-book-2019/