To make the custom player characters more interactive in cinematic discussions, voice recognition could be added, and the character on screen could mouth the words as they are spoken. For reference, here is a Skyrim mod that adds speech recognition so that you can speak the dialogue lines aloud to select them:
https://www.nexusmods.com/skyrimspecialedition/mods/16514Also, there should be different sets of dialogue choices depending on the player characters race, alignment and IQ level. A LE drow wizard with an IQ of 18 should have different dialogue choices than a CN halforc barbarian with an IQ of 3.
This, while cool and logical, would cost too much (game will have fully voiced custom - several variations of voices for female and male and then another set for origins). They said there will be no background-specific dialogues, because there are too many permutations already. So I would not expect dialogues depending on int, wis or char and alignment. There are some lines with race tag tho.
If I'm not mistaken, the reason Swen gave for scrapping background dialogue was that it would need to shoehorn the player into a specific backstory. He gave the example of the writers asking "ok, but how did the character become a Folk Hero? what was the heroic feat?" etc. when tasked with making the dialogue options. (I still think this could work with some consideration, but that's besides the point.) I wouldn't necessarily take this as a sign that they're unwilling to add any more complexity (although it may be the case. we don't know).
A bit more on topic: I'd only expect dialogue choices depending on race, class, gender, prior events and character knowledge. I think those are (mostly?) implemented already. Backgrounds if we can persuade Larian that it's doable, but I wouldn't count on it.
As for ability scores - I'm pretty sure Larian is dead set on all checks and check-like things being determined by rolls. So no special super intelligent dialogue for Int>18, but you can attempt to decipher an ancient text and succeed with your Int 3 half-orc. (Not a fan of this approach, personally.)
As for alignment - Swen has stated that they won't lock any dialogue options depending on a PC's alignment.