Reminder: This is only my personal speculation whose character there is no official confirmation from Larian Studios.
We know that the Bhaal spawn saga concluded in Throne of Bhaal, aka. ("Abdel Adrian's saga") as in official Forgotten realms canon.
Abdel Adrian as aka. Baldur's Gate Saga's character dies according to the official timeline at the module, murder at Baldurs gate thus his story is concluded his story. And Bhaal reborn as the god of Lord of murder. It is definitely concluded.
I think Larian should tell this part of the story as part of BG III in intro cutscene or something.
So we need a new character most likely in BG III. We know that the character is a player avatar, so there's no definition of who (he/she) is
but does need some kind "title" to hold that ties in the legacy of Baldur's Gate Saga. I have a suggestion according to that. Because there's not much info about what Does the "Abdel Adrian does after the events of Baldur's Gate games except, becoming a grand duke of Baldur's gate at some point in Faerun's history.
I have a suggestion that our protagonist in BG III is a child of ("Abdel Adrian") or a foster child of him. Thus tying the game into the Grand saga. And I'm not saying that what kind superpower or connection he/she have to special power to stop the Mindflayer invasion, but that I leave up to Larian's own creative team.
