So I've read some of the descent into avernus campaign, so I get those references but hey, it's been 100 years!
How's the politics different, is technology the same? Is Drizzit still Drizziting? Any fun wars or heroics? Gods still the same?
I assume we're all familiar with the first two games so, what else has changed since then that would be cool or helpful to know playing BG3?
Does WotC have other lore for these 100 years or is avernus all that's happened so far?
And if you know of events/changes/innovations/etc over that century, how would you like them referenced or reflected in game?
Off the top of my head the big bullet-points for me were
-The 'big one' for returning Baldur's Gate I and II players is Bhaal's back (along with some other gods). Canonically the bhaalspawn was the one from the books, and the pnp module featuring him ends with his death and Bhaal being reborn, as the final bit of essence (that I thought you gave up to Solar at the Throne of Bhaal, but whatever) is returned.
I get really peeved when people claim that idiot Abdel is the canon protagonist of Baldur's Gate 1 and 2. Even though he canonically existed in the lore, I argue that he canonically was not involved in the events of the games because in the Throne of Bhaal novel, he gave up his Bhaalspawn essence to the Solar to be a normal mortal too, so there is no way he could live to be in the Murder of Baldur's Gate tabletop adventure game. So, if he isn't the canon Bhaalspawn of the Baldur's Gate games, then who is?
That's easy. It's our player customized character. Because of the way Siege of Dragonspear ended, actually. See, Siege of Dragonspear is considered canon by Wizards of the Coast and Larian, so expect the events of that expansion to be mentioned in Baldur's Gate 3. The ending of Siege of Dragonspear had been hinted in the intro of Shadows of Amn even though Shadows of Amn came first (Beamdog wanted to tie up some loose ends), the people of Baldur's Gate figuring out that your character is a Bhaalspawn and being forced to leave Baldur's Gate on bad terms, so there is no way in the Nine Hells that the tall idiot Abdel from the Baldur's Gate novels is the canon Bhaalspawn protagonist, because the people of Baldur's Gate cannot EVER know that he is a Bhaalspawn, otherwise they would have him jailed and ready for beheading if he ever tried to return to Baldur's Gate after Throne of Bhaal. In Murder of Baldur's Gate, the game that heralds the return of Bhaal during the Second Sundering, Abdel is hailed as a hero and elected a Grand Duke! Why would they do that if they know he is a Bhaalspawn?
My point is, our player customized character and Abdel both exist. Our character's gender and race does not canonically matter in the lore because in the end, he/she becomes a fallen hero by the time the saga ends. Think about it. Our character is framed for murder of a child of a Grand Duke in the end of Siege of Dragonspear, and in Throne of Bhaal, our character is also accused of letting the fire giants decimate Saradush. Plus, the Bhaalspawn fire giant Yaga Shura knows our player character as the "Terror of the Sword Coast". After giving up godhood and having the Solar take our player character's and Imoen's portions of Bhaal's essence to Mt. Celestia, our player character develops a too negative reputation to live a peaceful life in Baldur's Gate, Amn and Tethyr, and lives a peaceful life somewhere else on Toril with their romanced companion or on their own, but Abdel would have a clean slate in his reputation, the people of Baldur's Gate could claim he is the hero who killed Sarevok and saved the city even if he was never involved. That can happen, you know. Some random guy getting the praise and fame for heroics he never did while the real hero fades into obscurity from the memories of the people and history books. All this would explain why Abdel lived for 100+ years to Murder in Baldur's Gate, because he still has his portion of Bhaal's essence in him, he never gave it up like in the Throne of Bhaal novelization.