The stats system of DKS worked perfectly
No it didn't, specially the "stat" system (though skills were great)! There is lots of scopes for improvements and should be exploited accordingly.
But I second your proposal of bringing back the familiar and important characters and not ONLY for reference's sake (i.e. good ol' stories of Rivellon).
About alternative endings, I can think of three -
1. the hero kills everyone (mostly innocent people) except Damien who lives to see another sequel!
2. the hero kills everyone including Damien but later realizes that it all was a dream and in reality he is imprisoned in a void only to freed before the next sequel!
3. the hero somehow manages to kill Damien by decoupling the soulforge between him and Larian but the folks at the studio resurrect their coveted ba(l)d guy and you're left with...well, you get it - another sequel!
Looking forward to Divinity -III
