Update: Bandai Namco shared a little more about what's coming in the Divinity: Original Sin 2 Definitive Edition today during the Judges Week event at E3. The game's third chapter is being completely overhauled, with rewriting, rescripting, and updated characters, and the journal is also getting an across-the-board rewrite. The map will have placeable markers, and a new "Party Inventory" option will eliminate the need to flip through individual inventory screens to find and move items.
There will also be a new tutorial, updates to the PvP arena, a new Story Mode difficulty setting (which I'm guessing will be similar to the Explorer Mode added to the Divinity: Original Sin Enhanced Edition, which simplified combat for players who are more interested in exploration, narrative, non-violent interactions, and all that), and DLC, including "Sir Lorna the Squirrel," a tale of a squirrel struggling with an existential crisis. That will be free for owners of the original as well.
Obviously we'll be hearing more about the Definitive Edition in the future, but it sounds like a major upgrade is on the way. Given the extensive work Larian put into the Divinity: Original Sin Enhanced Edition, I'm not surprised—and I'm really looking forward to it.
Divinity: Original Sin 2 is a really good game (we selected it as our game of the year for 2017, remember, and we can be pretty picky about these things), but apparently it's not quite good enough. Developer Larian Studios is working on a Definitive Edition version of the game that's set to come out in August for the Xbox One and PlayStation 4, and owners of the original on PC will get it as a free upgrade.
Larian revealed the Definitive Edition yesterday with a video introducing Feedback Billy, a new, more interactive system for collecting feedback on the game. The video only mentions the Xbox One version of the game (which will be available tomorrow via Xbox Game Preview), but over on Facebook the studio said that the updated release will be coming to PC as well.
The Divinity: Original Sin 2 Definitive Edition will be similar to the Enhanced Edition of Divinity: Original Sin, which came out roughly eight months after Divinity: Original Sin Classic, as it's now known. Both versions of the game will continue to reside on Steam, and you'll be able to launch and play either. Larian didn't say whether saves from the old version will transfer to the new, but since that wasn't the case with Divinity: Original Sin Enhanced Edition, I wouldn't expect it to happen here either.
It also didn't say what exactly is coming in the Divinity: Original Sin Definitive Edition, only that it will include "thousands of tweaks and changes." I'd expect a bit of new content too, but we'll have to wait and see about that. It's expected to be ready to go in August.