They said switching speakers mid-dialogue would lead to too many permutations to be able to do.
That's fine and understandable.
Is it tho? O_o
I mean ...
What permutations are they even talking about?
IM sorry, i dont really want to sound like ultimate sceptic ... but sometimes it feels like when Swen dont know what to say, just just come up with "oh many permutations and stuff you know, not worth it" *nervous laugh*.
Bare with me ...
You have any dialogue that gives you options ... there is few standard generic options, potentialy some ability checks, and class/race specific dialogues ... we dont really know, but since whole game is done trough tags, we can presume that Origin companions will be done in same way.
Now ... how does that look in practice?
I dont really know.

But i imagine it as something like this:
Gale: You are no Wizard are you?
1) I cant say i am.
2) The last thing i care about are some bloody Wizards.
3) [Warlock] I am better than Wizards, im a Warlock!
3) [Sorcerer] I am better than Wizards, im a Sorcerer!
4) [Shadowheart] blah blah blah.
4) [Astarion] blah blah blah.
4) [Lae'zel] blah blah blah.
4) [Wyll] blah blah blah.
4) [Karlach] blah blah blah.
And game is allways just checking what tags apply to your character, and hide those that dont ...
There will probably be some upgraded mechanism for hotkeys aswell, since we can have both Sorcerer and Warlock tags, so the game have to somehow give them proper numbers. But that is not a point here!
My question is ... where are those permutations?
I mean ...
If you are there as Tav, and just swap for Shadowheart for example ... all the game needs to do is simply make another tag-check and hide different ones ...
You are moving trough the dialogue exactly same way all the time, no matter who is the speaker ... the only thing that is changing is wich tags are visible and wich are not.