Far as I know, Larian cares about polishing up their games. D:OS and D:OS2 both got definitive editions down the line, though I do not know how much those added. I only played D:OS after the DE, and D:OS2 before the DE, which certainly felt a lot like BG3 when it came to the final act, but I only played that one full multiplayer so without origin companions.
Either way, it at least means they work on them post-launch. And since BG3 is a bigger project than likely D:OS and D:OS2 were combined, it's possible that the DE changes will also be larger.
Regarding changes, the easiest and most likely to happen (other than doing nothing) will just be changing triggers to have it no longer happen if you decline Halsin. This doesn't just account for Shadowheart; I think Halsin tries to force himself in during the drow twins conversation no matter the companion, though I might be wrong. I doubt the swimming dialogue will change. The rest is optional, player choice. I strongly doubt the story itself will get severe changes.
Though one can only hope things get changed for the better. Either way, I enjoy discussing and theorycrafting things, so this is entertaining to me all the same.
