What would be really cool is if Larian does what some other games like DA and Witcher have down, which is to include a survey for players at the start of the game asking them about some of the major choices they made in the first two BG games, so that some of that info could be factored into character, environment, and lore reactivities in BG3. For instance, if they had a question asking if your PC romanced Jaheira in BG2, then there could be some reference to that in BG3 if Jeheira is a companion who can be romanced by your BG3 PC. Something like, "Hey, you remind me of someone I was with for a brief time a century ago."
This could also go a long way to blunt criticism that BG3 is not very connected to the older games.
There is a problem and that is WotC. It is not known how much freedom Larian has in the case of canonical events.
After all, the canonical bhaalspawn was Abdel Adrian and I am betting two possibilities here, either he will be mentioned directly or the hero of the previous games will be completely left unmentioned.
In this case, Larian may have nothing to say.
