Well from the EA is pretty clear we'll end up in Baldur's Gate at some point and since a lot of races are long lived I'm expecting to see a familiar face or two. We also know that we're going to hell at some point too and not just in the intro.
There is 1 table top campaign bridging the gap between the end of BG2 and BG3. I'm hoping someone makes a youtube video covering the events in the table top campaign.