IF they eventually do Baldur's Gate 4...

... where do you suspect they might taking the story?

One thing I noticed is that there is a common theme of deism with all of the origin characters. Gale has the potential to defy Mystra; Lae'zel gets Vlaakith; Astarion has Mephistopheles to contend with; Shadowheart has Shar (though in a 4th, this could just as easily be Selune); and Karlach was enslaved by Zariel (Wyll gets Zariel too, but he's not cool enough to have his own arch-nemesis). I could see leveling up to 20 and going after more avatars.