I fail to see how a real Baldur's Gate 3 could ever exist, and I've never understood people who desire such a game.
At the end of Throne of Bhaal, the story is utterly over : the PC has either become a god or given up his bloodline to remain a mortal. A game where you play a D&D god could be interesting, but it would be completely different from the BG series. And even the ending where you remain a mortal certainly doesn't call for a sequel : ToB is already epic level D&D and you can't very well go beyond that.
So what ? A soft reboot ? A needless sequel in which, for some ridiculous reason, the PC loses all of his XP and regains his Bhaalspawn taint ? A story about the kid he has with (and after) fucking Aerie ? Something that mostly happens in the same region, features some of the old characters and has a few gratuitous ties to the original plot ? Or just something that happens in the Forgotten Realms and (like several other CRPGs that already exist) draws inspiration from Baldur's Gate ?
In any case, "Baldur's Gate 3" would be a blatant cash grab, the creation of someone who's realized that people are easily blinded by name recognition and nostalgia (as illustrated by several highly marketable movie franchises), and who would rather use that than try and stand on his own two feet.